have a thin time

(Brit. informal)have a wretched or uncomfortable time

(英，非正式)过得很不舒服

on thin ice

thin air

used to refer to the state of being invisible or non-existent

无影无踪，了无踪影；不存在

she just vanished &B{into thin air}.

她消失得无影无踪。

they seemed to pluck numbers &B{out of thin air}.

他们似乎在凭空拨弄是非。

the thin blue line

(informal)used to refer to the police, typically in the context of situations of civil unrest

(非正式)（多指社会动荡环境下的）警察

thin end of the wedge

thin on the ground

thin on top

(informal)balding

(非正式)头发稀疏的