required

adj.

必须的，（学科）必修的；

v.

要求( require的过去式和过去分词 )；需要；想要；命令

is required是必须的

as required按照规定；根据需要

required course n. 必修课程

documents required应具备单据；单据要求；所需要的单据

required power需用功率，需要功率

required value要求值；需求值；待定值

required subjects必修科目

required rate of return预期收益率，要求投资盈率；所需回报率，要求报酬率

1. I did more work than required.
   我做了比所被要求的来得更多的工作。
2. All passengers are required to show their tickets.
   所有乘客都必须出示车票。
3. 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。
4. The ships required the protection of naval and air power.
   船只本身需要海军和空军的保护。

PPAR gamma is required for placental, cardiac, and adipose tissue development.
Identification of ubiquitin ligases required for skeletal muscle atrophy
Identification of ubiquitin ligases required for skeletal muscle atrophy.
Fas(CD95)/FasL interactions required for programmed cell death after T-cell activation
Arabidopsis SGS2 and SGS3 Genes Are Required for Posttranscriptional Gene Silencing and Natural Virus Resistance
The Toll gene of Drosophila, required for dorsal-ventral embryonic polarity, appears to encode a transmembrane protein.
Two transmembrane aspartates in presenilin-1 required for presenilin endoproteolysis and gamma-secretase activity.
Recognition of commensal microflora by toll-like receptors is required for intestinal homeostasis.
Cell surface, heparin-like molecules are required for binding of basic fibroblast growth factor to its high affinity receptor.
Constitutive Nuclear Factor κB Activity Is Required for Survival of Activated B Cell–like Diffuse Large B Cell Lymphoma Cells