从玫瑰花、丁香花及紫苏中提取挥发油,适宜的提取分离方法有()。
A、水蒸汽蒸馏法
B、70%乙醇回流法
C、吸收法
D、压榨法
E、SFE法
参考答案:C, E
21st Century School Edition is ____ a newspaper. It helps us to improve our English a lot.
A.no less than
B.no more than
C.less than
D.more than
----Any news about Bill Clinton?
----He left power three years ago and has a little now and a little then been ______.
A.heard of since
B.heard since
C.heard before
D.heard of before