All _______they have done is goood for us.
A.what B.when C.why D.that
答案：A
what引导主语从句,在句中作主语.
The man _____gave us a talk on science yesterday is a famous scientist
A.who B.whose C.which D.whom
答案：A
who引导定语从句修饰the man.who是关系代词,指人.
Is there any fruit shop nearby_______we can buy some fruits?
A.at thay B.at there C.which D.at which
答案：D
at which 指：在在商店里.前面有介词at,所以不能用that.
I see no resoon ______this can not be done rigut now.
A.but B,why C.how D.which
答案：B
先行词是reason,关系副词用why.
That was _______I wanted
A.which B.the one what C.the one D.one which
答案：C
the one在句中作表语,后面是由that引导定语从句,修饰代词one,所以关系代词在句中作宾语,故省略.所以正确答案是C.