We cannot figure out ____quite a number of insects, birds, and animals are dying out.

 —So when did you meet Joan?—It was last Sunday _______ she came to visit my sister.

I don’t like the way ________ Mr. Wang treats his children.

I don’t like the way    he often uses to speak to me．

—What time will Mr. Brown be back to China? —Sorry. I don’t know______.