[yán cháng]
lengthen; extend; prolong; prolongate; elongation; extension; dwell; prolongation
									
										prolong the period of validity
										延长有效期
									
									
									
										The treaty has been prolonged for another ten years.
										条约延长10年。
									
									
									
										Period may be extended upon expiration (through agreement).
										通过协议可以延长期限。