【单选题】下列零件中尚未制定国家标准的是_______________。
【单选题】根据《旅游法》规定,旅行社应当按照规定交纳(),用于旅游者权益损害赔偿和垫付旅游者人身安全遇有危险时紧急救助的费用。
【单选题】Don't worry. She can look after your pet _____. [ ]
【单选题】当镜眼距为12mm,框架眼镜屈光度为+3.50D,此时接触镜屈光度为
【单选题】Be careful. Don't ______ your drink on the table.
【单选题】当镜眼距为12mm,框架眼镜屈光度为-6.00D,此时接触镜屈光度为
【单选题】Be careful next time;_______?
【单选题】If you _____ careful, you will have an accident. [ ]