required

动词 require:

1. require as useful, just, or proper
   同义词：necessitate, ask, postulate, need, require, take, involve, call for, demand
2. consider obligatory; request and expect
   同义词：ask, require, expect
3. make someone do something
   同义词：command, require, compel
4. have need of
   同义词：want, need, require

形容词 required:

1. necessary for relief or supply
   同义词：needed, needful, requisite
2. required by rule
   同义词：compulsory, mandatory

1. Learning to walk again after his accident required great patience.
   他出事后重新学习走路要有极大的毅力。
2. His work does not reach the standard required.
   他的工作成绩达不到要求。
3. I did more work than required.
   我做了比所被要求的来得更多的工作。
4. All passengers are required to show their tickets.
   所有乘客都必须出示车票。
5. We are required by environment protecting department to use anthracite.
   环保部门要求我们使用无烟煤。
6. The ships required the protection of naval and air power.
   船只本身需要海军和空军的保护。
7. The order No.105 is so urgently required that we have to ask you to speed up shipment.
   第105号订单所订货物我们要急用，请你们加快装船速度。
8. Being a substance that is required for normal functioning but does not need to be included in the diet because of the body's ability to synthesize it from other nutrients.
   (氨基酸)非必需的是正常的运转所需要的物质的，但因为机体有从其它营养成分合成它的能力，因此不需要被包括在日常的食物中的

re.quired

adj.Abbr. req.,reqd.（形容词）缩写 req.,reqd.
Needed; essential.
必需的；必不可少的
Obligatory:
必要的：
例句：
required reading.
必读物