题目内容：

Things from Earth are ____ on Mars.A.hardly to find B.hard to find them C.hard to find D.hardly
finding

优质解答

C
.hard形容词做表语 to find 不定式做状语；而hardly是副词“几乎不”,不能做表语用；现在分词的finding只能做时间和伴随状语,to find them中的them是多余的