下列哪种溃疡病最易发生大出血
A．十二指肠球部溃疡B．十二指肠球后溃疡C．胃小弯溃疡D．幽门管溃疡E．复合性溃疡
参考答案：B
Concerning the payment for the machines to be imported by us, we suggest that we make payment ______ three annual installments without interest.A．byB．withC．for D．on
液膜分离技术一般有（）。
A.肥皂液膜
B.乳状液膜
C.高分子液膜
D.支撑液膜
