_____ many people here on vacation [ ]
A. They're
B. There are
C. There is
D. There be
答案:B
睾丸
A.人绒毛膜促性腺激素B.人胎盘生乳素C.雌激素D.孕激素E.前列腺素
若a+b+c=0,求(a+b)(b+c)(c+a)+abc的值.