Scientists now know that the lack of an embryonic thumb ...

[ Grammar ]

Scientists now know that the lack of an embryonic thumb in birds is why ____ almost impossible for birds and dinosaurs to be related.

A. is

B. it is

C. is it

D. it

Select your answer:
A B C D E

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He has to _________ the plants twice a day.

A. water

B. waters

C. watered

D. watering

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