a straight back的用法和样例：
- A straight back is not desirable, this formation being unsuited for uphill work, and very unsightly.
- She say with a straight face she see green spacemen in the back yard.
- I just want a straight answer to the question.
- He drew a straight line on the paper.
- Age had bowed his once straight back.
- Stop flannelling and give a straight answer!