I realized that I (forget) to thank them. Which ...

★ Past Perfect Simple & Past Perfect Continuous

I realized that I (forget) to thank them.

Which is the correct past perfect simple for the sentence above?

A. had forget

B. has forgotten

C. having to forget

D. had forgotten

Preview next quiz:

Which of the sentences below uses past perfect continuous?

A. The chefs had cooked all day before the party began.

B. The chefs had been cooking all day before the party began.