美 
											[kən'streɪn]
																
										
							hold back or force into an unwanted action, by limiting sb's freedom to act or choose
																																	"Tighten the rules"
																							"stiffen the regulations"
																															
Some rule, that guides, but not constrains.
出自: Pope
The season constrained them to carry on the harvest.
出自: J. Fuller
警察骑着马阻止那群人诉诸暴力。