维生素D缺乏性手足搐搦症的主要死亡原因（）
A.脑水肿
B.喉痉挛
C.心力衰竭
D.呼吸衰竭
E.吸入性肺炎
参考答案：B
The sun was shining brightly, _____ everything there _____ more beautiful.
A．making; look
B．to make; looked
C．and made; looking
D．and making; be looked
简述交流励磁机励磁系统的优缺点。
