As a poet, Ted Hughes had an acute sensitivity to the way in which constraints on self-expression, like the disciplines of metre and rhyme (韵律), spur creative thought
出自-2013年12月阅读原文
Compared with a hundred years ago, our lives are less tightly bound by social norms and physical constraints
出自-2013年12月阅读原文
And scientists are only just beginning to understand what those constraints are.
2018年6月六级真题（第一套）阅读 Section C
柯林斯高阶英汉双解学习词典释义
N-COUNT
限制;束缚;约束
A constraint is something that limits or controls what you can do.