葡萄胎特征性声像图的表现是()
A．子宫大于孕周
B．双侧卵巢囊肿
C．宫腔内见蜂窝状无回声区
D．子宫肌层回声不均
E．胎囊形态不规则
参考答案：C
According to a survey, homework is_____ students most often blame for their lack of sleep.[ ]
A. what
B. that
C. which
D. why
炉缸燃烧初期的产物是（）。
A、CO2
B、CO
C、H2
D、N2
