He pretends to busy himself writhing.请问这里面to有什么用?直接去掉可以吗?为什么

翻译：But Miss Minchin,who owns the school,just pretends to like Sara.
谢过~~~

she pretends___this matter at all ,althouugh she knows that I'm very worried adout that
A to not knows
B not know
C not to know
D not knoeing

英语翻译
1,he drank himself out of the best line.
2,he pretends to be as modest as anything.
3,Fire goes whereever it can,but it prefers to follow a draft.
4,the room was easily fraced by the noise that was coming form it.

The dog pretends _____. Maybe it will bark _____ you.

[ ]

A. to be sleeping, ／ B. to be sleeping, at C. be sleeping, at D. be sleeping, ／

He pretends ____ the whole thing. A.didn＇t know B.doesn't know C.not knowing D.not to know
答案是C,为什么不能选D,请详细说明、解析

英语翻译
When asked by his headteacher,he often pretends as if he were ill.
请标准翻译,尤其是“as if he were ill”.

every time he is asked to do some house work,he pretends ____ with his work.
a.to be busy b.being busy c.to have been bysy d.busy