"二尖瓣型心"的基本特征是（）
A.右心室增大
B.肺动脉段膨隆
C.主动脉结突出
D.右心房增大
E.心尖向左下延伸
参考答案：B
Helen, ________ her mother, ________ dancing very much.
A．likes; likes
B．like; like
C．likes; like
D．like; likes
要约是指受要约人同意要约的意思表示。
