下列塑料中最适宜用作安全防护头盔的材料是（）。
A.ABS工程塑料
B.环氧树脂
C.尼龙
D.聚碳酸酯
参考答案：D
With a lot of things ， John will have a difficult time.
A．to deal with
B．deal with
C．dealing with
D．dealt with
哮喘病人全身麻醉应禁用哪种药
A．γ-羟丁酸钠B．氯胺酮C．琥珀胆碱D．芬太尼E．硫喷妥钠
