a weak constitution的用法和样例：
- A weak constitution disposed her to frequent illness.
- A hard life and a weak constitution shortened his life.
- The child has a weak constitution and is struck ill from time to time. Lack of exercise is part of the reason.
- Women with a weak constitution should take medicines with the effect of replenishing vital essence, tonifying kidney-yin and nourishing the Bone marrow.
- He has a weak constitution.