问题

The scientists all over the world are trying their best to develop _____ energy, such as sunlight, wind and water for power and fuel. [ ]

A: unique
B: alternative
C: primary
D: instant

正确答案是：

同类题型

at the government can lead them out of the financial crisis,people are optimistic about the future of the country

edtogethomebeforedark,butitdidn’tquite________asplanned

I’ll give you a phone call toParis.

I used to quarrel a lot with my parents, but now we_______ fine.

Shall we go for a during at one o’clock thisafternoon —_______.Will two o’clock be OK