Question

They _________ the habit of visiting old friends,_________ I think is great.?

A．keep on;which	B．keep up;which?
C．keep on;as	D．keep up;as ?

Answer 1

B?

keep on有继续之意,常用于keep on doing中,keep up是维持、保持的意思。本题是“保持习惯”的意思。which与as都可引导非限制性定语从句,但在从句中作主语时常用which,且as常有“正如……,像……一样”的意思。