尿素合成的主要器官是（）
A.肝脏
B.肾脏
C.肌肉
D.心脏
E.胰腺
参考答案：A
固态的凝集性气溶胶称为（）
A.气体
B.蒸气
C.雾
D.烟
E.尘
With so many people __________ in English every day, it will become more and more important to have a good ___________ of English.
A．communicate, knowing
B．communicated, knowledge
C．communicated, knowing
D．communicating, knowledge
