做砂子的颗粒级配试验时,如果两次试验的细度模数之差超过()时,须重新试验。
A. 0.10
B. 0.15
C. 0.20
D. 0.50
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If the surveyors ()yesterday, they would have finished the survey work.
A. did not interrupt
B. were not interrupted
C. had not interrupted
D. had not been interrupted
一国居民出国旅游属于()。
A. 调节性交易
B. 补偿性交易
C. 事后交易
D. 自主性交易
不利于柑枯黄龙病发生和流行的条件有()
A. 有良好防护林
B. 湿度较小的果园
C. 幼龄树果园
D. 挂果多的果树