Question

she was worried about ( )shecould finishthe work in time a.that b.what c.if d.whether

选什么？为什么？she was worried about ( )shecould finishthe work in time
a.that b.what c.if d.whether
( )we got home it was very late.
a.when b.while c.because d.as
when while有什么区别?

Answer 1

第一题选D
句子意思为，她担心她是否能够及时完成工作
这题首先排除的是A.B两个选项，意思代入，不对的
而C.D两者都可以表示是否，但是whether可用在介词之后，引导宾语从句，而If则不能。
e.g. Success depends on whether we make evough effort.

第二题选A
这题首先排除的是C
剩下when while as三者之间的区别
while只指"时间段"，不指"时间点"，从句的动词只限于持续性动词或者进行时
e.g.While we were still laughing, the teacher came in.
e.g.While I slept, a thief broke in.(sleep持续性动词）

when意为"在……时刻或时期"，它可兼指"时间点"与"时间段"，所引导的从句的动词既可以是终止性动词，也可是持续性动词。
When I got home, he was having supper.我到家时，他正在吃饭。
When we were dancing，a stranger came in．

as表示两个动作同时发生：一个主语同时进行两个动作：一种状态随另一种状态的变化而变化。
As he stood there, he saw two men enter the bar.(stood跟saw同时进行）
As it grew darker it became colder.（随着天变黑，越来越冷了 ）

Answer 2

选D whether如果选that中文意思就是，她担心她能按时完成工作，意思显然不对，她是担心她能否按时完成，只有whether有是否的意思，what应该是在从句里作为助于或者宾语，但是she could finish the work 是一个完整句子，所以不能用what,再说what放在句子里意思也不对

when while区别最简单的方法就是，while后面一般接一个持续性动作的进行时，如while I was watching TV, someone knocked at the door