某公路段施工中,计划时段内应完成的工程量户,计划时段内的制度台班数W1,机械的台班生产率Q,机械的利用率足KB,则需要机械的台数N为()。
A.A
B.B
C.C
D.D
参考答案:D
His mother always tells him that he should be more careful, but ____ doesn't work. [ ]
A. which
B. she
C. he
D. it
不能刺激T细胞的丝裂原是()
A.植物血凝素
B.刀豆蛋白A
C.美洲商陆
D.脂多糖
E.花生凝集素