There is no doubt________man will continue to explore the vast universe in the future, but the rate at which we approach depends on the development of technology.[ ]

Frank, you look worried. Anything wrong — Well, I______ a test and I’m waitingfor the result．

Alice, you feed the bird today, ______?—But I fed it yesterday.[ ]

We’ll learn _____ benefits us no matter which country it comes from.

We didn’t know his telephone number, otherwise we ________ him.