能促使胃蛋白酶原转变为胃蛋白酶的物质是
A．盐酸 B．前列腺素E2 C．丙谷胺 D．内因子
参考答案：A
65. The Chinese people _____ brave and hard-working. The Chinese _____ a brave and hard-working people.
A．is; are
B．are; are
C．are; is
D．is; is
牵引机牵引卷筒槽底直径不得小于被牵引钢丝绳直径的（）倍。
A.10
B.20
C.25
D.22
