The shop is _______ on Saturday and Sunday. We cango shopping there on weekdays.—Oh, no. It sincelast Saturday.

Experiments of this kind ________ in both the U.S. and Europe long before the Second World War.

Scientists generally agree that Earth’s climate will warm up over the next 50 to 100 years ________ it has warmed in the 20,000 years since Ice Age.

the environment of fiercecompetition, the only way John could imagine _______ stress was to get tougherby making greater efforts.

Let’s sing along______the music, OK—That’s a good idea.