是松，loosen 意思是松开、解开，例如：

1.The military regime has not loosened its hold on power.军事政权尚未放松对权力的控制。

2.Many business groups have been pressing the Federal Reserve to loosen interest rates.不少企业集团一直在向联邦储备委员会施压，要求其放松利率管制。

3.First loosen the nuts, then take off the wheel.先松开螺母，然后卸下车轮。