It is in London _______the 2012 Olympic Game will be held.

1 B
“It is+被强调部分+that+其余部分”是强调句型.
这题如果London前面没有in,就是单纯指地点了,就要选A了.被强调部分有没有介词很重要.
2 A
what it was fifty years ago前面有个系动词is,可见what it was fifty years ago是表语从句.B、D两项不引导表语从句,可以排除.that引导表语从句时本身无意义,在从句里不充当任何成分,只起连接作用.what引导表语从句时要充当主语、宾语或表语.
it was fifty years ago缺了表语(只有系动词was,没有表语）,填what.
3 C
定语从句的先行词为everyone 时,定语从句用who（在从句中作主语）或whom（在从句中作宾语）引导,who或whom都可以换成that.题中定语从句缺主语,填who或that.

1.C
held in London,原句不缺少介词in,所以用which
2.C
no longer ：不再
that指 it was fifty years ago.
3.A
everyone是人嘛，所以用whom
在这种句子中，修饰人时用who/whom
修饰物时用which
that既可修饰物，也可修饰人
w...

1 B It ......that......是强调句型，用来强调地点 in London
2 A what 作主句的表语，作从句was的宾语
3 C 定语从句中先行词为everyone 时，用that引导