问题

We cannot figure out _____ quite a number of insects, birds, and animals are dying out [ ]

A: that
B: as
C: why
D: when

正确答案是：

同类题型

Where’s Li Hua—Look! He _______ tennis on the playground.

He used to ____late, but now he is getting used to _______early.

Never in the past twenty years________so greatly as today. [ ]

Where did you come across our Chinese teacher — It was in the supermarket ______I purchasedmooncakes．

Mr. Putin told CNN in an interview that the United States should not ________ in Russia’s internal affairs.