以猪作为主要传染源的病毒是
A．流行性乙型脑炎病毒B．登革病毒C．森林脑炎病毒D．汉坦病毒E．新疆出血热病毒
参考答案：A
若n边形的内角和是它外角和的2倍，则n=______．
This cake is very sweet. You _________ a lot of sugar in it.
A．should put
B．could have put
C．might put
D．must have put
