We don’t write to each other regularly.but we do keep intouch by telephoning .A.
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We don’t write to each other regularly，but we do keep intouch by telephoning _____.
A.at a time
B.once
C.at once
D.once in a while
试题答案
D
once in a while“间或，偶尔”;at a time 每次，一次；once 一旦；at once 立刻，马上。题意为：我们不经常相互写信但我们偶尔会通电话。