Question

Diamond, ______, is the hardest of all materials.

1. A.
   like we know
2. B.
   since we know
3. C.
   we know
4. D.
   as we know

Answer 1

D
定语从句题。先行词是整个句子时关系词只能用as，所以要选D。 正如我们知道的那样钻石是所有材料中最硬的。