已知一个mRNA中有1200个核苷酸，那么他的基因双链中G和T的总数为：（） ["600","1800","300","1200"]
在格式化磁盘时要注意，认为（）是错误的。 ["不同操作系统下格式化的软盘是不可通用的","写保护装置起作用的磁盘无法被格式化","格式化一个磁盘将破坏磁盘上的所有信息","在DOS下被格式化过的磁盘不能在其他种类的微机操作系统下被格式化"]
Which statement concerning the lashings of containers with solid bar or wire rope lashings is TRUE? （） ["Stack weights should be less when using a solid bar lashing as compared to a wire lashing","Stack heights may be increased when using a solid bar lashing","Stack heights should be reduced when using a solid bar lashing","Solid bars should be used for lashing the first tier only，with wire lashings on the higher tier(s)"]
国家规定相关产品必须经过认证的，应当经过认证并标注认证标志后，方可（）或者在其他经营活动中使用。 ["出厂","销售","出口","进口"]
埋弧自动焊生产率高的主要原因是（） ["采用了粗焊弧","选取了大电流","电弧电压高","焊接温度低"]
通用计量器具按工作原理可分为几类？
