碎煤机一般震幅不超过()。
A、0.01;
B、0.025;
C、0.03;
D、0.15。
参考答案:B
It was not until she came to see us ____ her mother was ill in bed.
A.when we knew
B.that did we knew
C.that we knew
D.that did we know
Living in the country,Peter doesn’t write often,but we do hear from him________.
A.now and then
B.sooner or later
C.at the same time
D.more or less