slack off 懈怠
loosen up 放松
slacken 变松
relax 放松
1. You should slack up the rope a little bit.
你应该把绳子稍微放松一点。
2. Don't slack up on your studies now.
现在不要在学业上懈怠。
3. The tension in the wire began to slack up.
电线的张力开始变松。
A: The knot is too tight. Can you slack it up?
A：这个结太紧了。你能把它放松一点吗？
B: Sure, just a little bit.
B：没问题，就稍微放一点。
1) 使松弛
2) 放宽限制
3) 懈怠
1. 使松弛；放宽
e.g.
Slack up the sails to reduce speed.
放松风帆以降低速度。
phrasal verb
1. To make something less tight or less strict.