21．If you feel any ______ in your neck, put a towel under your head for support when sleeping.
A．tension B．abortion C．submission D．dimension
22．Nowadays, many people struggle to maintain the ______ balance between work and family.
A．deliberate B．delicate C．desperate D．definite
23．Not well prepared for this lecture, he had to ______ his memory by looking at his notes.
A．refresh B．relax C．relieve D．register
24．We didn't travel much during the holiday, ______ because of the tight budget, but also because of the huge crowds.
A．in turn B．in vain C．in part D．in effect
