切制抗坟试件法测试设备应选择适宜吨位的长柱压力试验机,预估抗压试件的破坏荷载值应为压力试验机额定压力的()。
参考答案:20%~80%
_____________ the Games will be held in Beijing is not known.
A.Whenever
B.If
C.Whether
D.That