Cars make our life easier, _________ they bringenvironment problems.

Lucy had few close friends. So she didn’t know ________ about the trouble.

The composition is well written ___________ afew spelling mistakes．

How can the spaceman ____ when he spends months in space without the atmosphere’s protection? [ ]

We all think it is Mr Wang as well as hisparents that _______ for his son’s bad performance at school.