----------has he been to the pyramids in Egypt? Only once A.

B.How many times
Only once只一次.
自然是问:去过多少次?
A.How often 是问频度的,多久去一次.
再问： _____you be able to work out this Maths problem by yourself? A.Will B.Are C.Can D.Could 选什么
再答： A 你能独立做出...吗? be able to 用了原形,已经有BE了.所以B不对. can =be able to C和D不对.