好发于儿童及青少年的卵巢肿瘤是（）
A.浆液性囊腺瘤
B.黏液性囊腺瘤
C.卵巢内膜样肿瘤
D.生殖细胞肿瘤
E.恶性间质肿瘤
参考答案：D
Many people in China have never dreamed of ________ a chance for them to learn to drive after their
retirement.[ ]
A．being
B．there
C．there to be
D．there being
装置引蒸气时所要进行的操作有：（）。
A、排凝
B、暖管
C、检查保温
D、检查流程
