The number of people invited fifty, but a number of them absent for different reasons.
A. were；was
B. was；was
C. was；were
D. were；were
网友回答
A. were；was
B. was；was
(答案→)C. was；were
D. were；were
解析：the number of（。。。的数量）+可数名词复数+单数谓语，a number of（许多，若干）+可数名词复数+复数谓语，句意：被邀请的人有50个，但有若干人因为不同的原因缺席。