对工厂职工目前的健康状况进行的调查
A．横断面调查B．病例对照调查C．队列调查D．职业病普查E．前瞻性研究
参考答案：A
The number of teachers in our school _____ greatly increased last term. A number of teachers in this
school _____ from the countryside.[ ]
A. was; is
B. was; are
C. were; are
D. were; is
PKU的临床表现有______、_______、_______，____________。
