贸易融资贷款形式主要有()
A.信用证
B.保理
C.贷款承诺
D.福费庭
参考答案：A, B, D
如图所示表示不同温度下酵母菌发酵时气体产生量与反应时间的关系。由图可知
①有多种酶参与 ②最适pH是7 ③最适温度是40℃左右 ④50℃时酶逐渐失活 ⑤0℃时酶逐渐失活
A．①③
B．②⑤
C．③④
D．④⑤
His sister left home in 1998，and_______since．
A．had not been heard of
B．has not been heard of
C．had not heard of
D．has not heard of
