四大标准的编制和执行的特点:保证其有效性、切实执行和()。
参考答案:持续完善
根据下列句子及所给首字母,写出单词的适当形式,每空一词。
小题1:We have three m________ a day. They are breakfast, lunch and supper.
小题2:They took quite a f_______ photos in Guizhou.
小题3:I d_______ playing computer games. I think they are boring.
小题4:I exercise t________ a week, every Wednesday and Friday.
小题5:It is sunny today, so it is not n_________ for you to take an umbrella.
有些材料在温度很低的情况下电阻为零,这种材料叫超导材料.假如科学家在常温下研制出这种材料,那么它合适制作( )
A.白炽灯的灯丝
B.加热器的电热丝
C.熔断器的熔丝
D.输电线的导线