下列图形中，是轴对称图形的有
①锐角；②线段；③等腰三角形；④等边三角形；⑤平行四边形． [ ]
A．1个
B．2个
C．3个
D．4个
答案：D
I am afraid that your request to speak at the ceremony is not quite _______, because we have already had everybody _______ ______. [ ]
A. in place; speak; in place
B. in place; to speak; in place
C. out of place; speaking; in place
D. in place; to speak; in the place
下列脂肪酸哪些属于必需脂肪酸()
A.棕榈油酸(C16:1)
B.亚油酸(C18:2)
C.花生四烯酸(C20:4)
D.硬脂酸(C18:0)
E.a-亚麻酸(C18:3)
