问题

Every possible means _____ to prevent the air pollution, but the sky is still not clear. [ ]
A: is used
B: are used
C:/T
D: have been used
B: are used
C:/T
D: have been used
正确答案是:
同类题型
I’d appreciate _____ if you could turn the radio down. I’m doing my homework.[ ]
It’s ______ to sign up for the cooking contest when you can’t cook a meal by yourself.
I thought she was famous, but none of my friends have ______heard of her
It’s such a good place ______ everybody wants to visit _____ it is well known all over the world