急求！~九年级英语试题（4道句型转换，能解释尽量说明一下）

1.My mum loves wearing shoes.The shoes have low heels.(合并为一句）
My mum loves wearing shoes___low heels.
2.The bookcase is used for {keeping books}(对括号内部分提问）
___ ___ the bookcase___ ___?
3.The machine which is used to catch mice was invented by [a farmer].（对括号内部分提问）
___ ___ the machine which is used to catch mice invented by?
4.A boy broke the glass.(改为被动语态）
The glass___ ___ ___a boy.

with

with做介词时，可理解为“有”，和原题中的have对应。

What is. used for

keeping books为动名词短语，表示sth，当然用what来代替提问

Who/Whom was

可简化为对The machine was invented by a farmer.的提问

a farmer指人sb，并充当by的宾阳，所以用whom，口语中用who亦可

was broken

被动语态结构为“be + 过去分词”，原句为一般过去时，且主语the glass为单数。所以改成was broken。