Be apprehensive of and Hang by a thread

Hang by a thread and be apprehensive of are semantically related. In some cases you can use "Hang by a thread" instead a verb phrase "Be apprehensive of".

Hang by a thread verb - Depend on a small thing or be at risk.

Be apprehensive of and hang by a thread are semantically related. Sometimes you can use "Be apprehensive of" instead a verb phrase "Hang by a thread".