英语单选.

英语单选.
1)—You‘ve dropped ____“s” in the word “necessary”
—Oh ,____ letter "s" is doubled.
A.a ; a B.a; the C.an ; the D the ; the
2)" What time do you usually get up ,John " " I usually get up at____"
A .half past six B .half to six C.half after six
3)It took us ___ to get to the top of the mountain last Sunday.
A.one hour and a half hou
B.one and one half hours
C.an hour and a half hour
D.one and a half hours