Sometimes the charter-party states that the amount of cargo to be loaded is to be decided by the shipowners，e.g. 10000 tons of 2240 1b.，12％ more or less at（）option. ["Charterer's","cargo owner'","owner's","shipper'"]
师生之间行握手礼时，应是（） ["以学生先伸手为礼","以老师先伸手为礼","无所谓"]
井下落物按其性质，大致可分为杆类落物、（）四类。 ["管类落物、软体落物、小件落物","管类落物、软体落物、绳类落物","绳类落物、小件落物、管类落物","绳类落物、小件落物、软体落物"]
国际航行船舶的船长，必须每隔（）向卫生检疫机关申请一次鼠患检查。 ["3个月","6个月","9个月","1年"]
Most solenoid valves are actuated by （）. ["a spring","an electromagnet","the force of gravity","refrigerant pressure"]
过机误差分为滞后误差和（）两种。
