TOEFL iBT Reading · Reading Comprehension

Reading Comprehension

53 sets — answer the whole set, then submit once for your score, scored privately in your browser.

Ordered easiest → hardest (estimated from text complexity).

Easier

Why do researchers give some trial volunteers a dummy pill?

Easier

According to the passage, why is planting corn after beans beneficial?

Easier

According to the passage, what is released into the atmosphere during photosynthesis?

Easier

According to paragraph 2, what force do the main cables of a suspension bridge primarily experience?

Easier

According to the passage, what was the primary function of the wedge-shaped mark used by Babylonian scribes?

Easier

According to paragraph 1, why does photorespiration increase in C3 plants under hot, dry conditions?

Easier

The word "viscosity" in paragraph 2 is closest in meaning to

Easier

According to paragraph 1, what enabled Andean farmers to store potatoes for extended periods?

Easier

According to paragraph 1, why did guilds emerge in medieval towns?

Easier

According to paragraph 2, what role does the ocean play in the fast carbon cycle?

Easier

Based on paragraph 2, what determined when ships could sail between the Red Sea or Persian Gulf and India?

Easier

According to paragraph 2, what evidence did researchers originally cite in support of the Botai culture as…

Easier

According to paragraph 2, what is the function of the iron-based mineral deposits found in the upper beak o…

Easier

According to paragraph 1, when is the temperature difference between urban and rural areas typically greatest?

Easier

According to the passage, what was Samuel Morse's crucial contribution to the development of the telegraph?

Easier

According to paragraph 2, how does a horn typically form?

Easier

According to paragraph 1, what does sericulture require in order to produce silk commercially?

Easier

According to paragraph 1, what proportion of described insect species undergo metamorphosis?

Medium

According to the passage, what problem did Nicéphore Niépce solve with his heliography process?

Medium

According to paragraph 2, what does the polyp provide to the zooxanthellae in exchange for organic compounds?

Medium

According to paragraph 2, what happens to hydrothermal fluid when it is expelled from a vent into the surro…

Medium

According to paragraph 1, what did Alfred Wegener propose in 1912?

Medium

Why does the author mention that similar solutions have arisen in unrelated desert organisms in paragraph 1?

Medium

According to paragraph 1, what is the 'active layer'?

Medium

According to the passage, how did the flooding pattern of the Tigris and Euphrates rivers differ from that…

Medium

According to paragraph 1, what accounts for the ability of tectonic plates to move across Earth's surface?

Medium

Based on paragraph 2, what distinguishes semantic memory from episodic memory?

Medium

According to paragraph 1, what causes chromatic aberration in refracting telescopes?

Medium

According to paragraph 1, what characterized cloth production before mechanization?

Medium

According to paragraph 2, what allows barnacles and mussels to survive in the middle intertidal zone?

Medium

Based on the passage, why could determining longitude not be solved simply by better mathematics?

Medium

According to paragraph 1, why are seeds that fall directly beneath the parent plant at a disadvantage?

Medium

The word "fragments" in the passage (as used in reference to rock breaking apart, Paragraph 1) is closest i…

Medium

According to paragraph 1, what has uranium-thorium dating contributed to the study of cave art?

Medium

According to the passage, what was the primary force that moved water through the Roman aqueduct system?

Medium

According to paragraph 2, why did the North American beaver's fur become especially valuable to European ma…

Harder

According to paragraph 2, why do wind-pollinated plants typically produce very large quantities of pollen?

Harder

According to paragraph 1, what determines whether ring width in a given region correlates with precipitatio…

Harder

According to paragraph 1, why was access to books limited before the mid-fifteenth century?

Harder

According to paragraph 2, why did merchants in Tang dynasty China begin using receipts known as "flying mon…

Harder

According to paragraph 1, what evidence indicates that bacterial resistance is not solely a product of mode…

Harder

According to the passage, why is the monarch migration considered puzzling to biologists?

Harder

According to paragraph 2, what is the primary function of the clicks that sperm whales produce while foraging?

Harder

According to paragraph 2, what tasks did apprentices typically perform before being allowed to work on comm…

Harder

The word "incidental" in paragraph 3 is closest in meaning to

Harder

According to paragraph 2, what evidence do researchers cite for a possible shared cognitive resource betwee…

Harder

According to paragraph 1, how did the Mesopotamian city-states typically relate to one another politically?

Harder

The word 'stimulus' in the phrase 'stimulus diffusion' in paragraph 1 is closest in meaning to

Harder

According to paragraph 2, why was Fleming unable to develop penicillin into a usable drug after his 1928 ob…

Harder

According to the passage, what problem had earlier experimenters failed to solve before the Wright brothers…

Harder

According to the passage, all of the following are mentioned as historical census-related documents or syst…

Harder

The word "persistent" in the passage (describing the zone of low atmospheric pressure) is closest in meanin…

Harder

According to paragraph 1, what does effective background matching require beyond simple color similarity?