1、use的形容词是usable（=useable）、useful和useless。
2、usefullife:使用答寿命|有效寿命|有用寿命。
3、usefulload:有效载荷|有效负载|有效荷载。
4、makeoneselfuseful帮忙。
capable of being put to use;
"usable byproducts"
fit or ready for use or service;
"the toaster was still functional even after being dropped"
"the lawnmower is a bit rusty but still usable"
"an operational aircraft"
"the dishwasher is now in working order"
convenient for use or disposal;
"the house is available after July 1"
"2000 square feet of usable office space"
use这个单词呢，既可以是动词，也可以是名词。一般的构词法都是在动词后边加ful变成形容词。例如help形容词形式是helpful,harm是动词，harm的形容词形式是harmful, Care也是动词,它的形容词形式是careful，所以说use的形容词形式应该是useful。
