3-6岁幼儿以（）为主，注意稳定性差，容易转移。
A.无意注意
B.有意注意
C.有意后注意
D.意义注意
参考答案：A
下列哪项引起左心室后负荷增加()
A．主动脉瓣关闭不全
B．肺动脉瓣狭窄
C．三尖瓣狭窄
D．主动脉瓣狭窄
E．动脉导管未闭
—It never snows in winter in Hainan, _____?
—Yes, so people in Harbin like traveling to Hainan in winter. [ ]
A. is it
B. doesn't it
C. does it
