To be frankly speaking, it is thoroughly _____ to sit on the sofa and watch some entertaining TV programmes

after a hard day's work. [ ]

A. confusing

B. relaxing

C. terrifying

D. surprising

如图所示电阻的等效电阻Rab为（）。

A.3.3Ω；

B.2Ω；

C.5.5Ω；

D.4Ω。