---_______do you send e-mails to your pen friend? ------Once a month.
#56239
A
How long
B
How far
C
How much
D
How often
推荐题目
—Would you like to go hiking with us this Sunday? —Sure, _______ I am busy.
#57786
A
until
B
when
C
unless
D
since
Tony is an English boy. He can speak English, ______ he can’t speak Chinese.
#56312
A
and
B
but
C
too
D
so