答案:B
How long ______ teaching? Forty years.
A.he will have been
B.will have he been
C.will have been he
D.will he have been
聚山梨酯类属于()
A.油脂性基质
B.O/W型乳剂基质
C.W/O型乳剂基质
D.水溶性基质
E.聚乙二醇基质