A number of my friends think I should take a holiday.为什么加s
问题描述：
A number of my friends think I should take a holiday.为什么加s
A number of my friends think I should take a holiday.friends为什么加s
答
a number of 意思是“许多,大量的”,所以后面接可数名词的复数形式.a number of 后边用is还是areareA number of students are swimming in the pool.