吐温-80（HLB=15.0）2g和司盘-80（HLB=4.3）3g混合后的HLB值为（）

A．9.65

B．8.58

C．21.45

D．3.86

E．10.7

With an eighty-hour week and little enjoyment, life must have been very________ for the students.

A．hostile

B．anxious

C．tedious

D．obscure