Smoking and drop behind during marching were risk factors with OR 1.67 and 1.70 respectively.
应力性骨折的危险因素为吸烟和入伍后跟不上行军速度，OR值分别为1.67和1.70 ；
Try to toss the ball into the same spot every time? Let your racket head drop behind you and then hit the ball suddenly.
尽量在发球时每次都把球抛到相同的位置，然后将球拍举到头后方，瞬间击球。
He shuffled along behind his brothers careful not to drop behind. Not a syllable of complaint escaped his lips.
他慢吞吞地跟在哥哥们的后面，努力不被他们落下，但他一句抱怨的话都没说。
He shuffled along behind his brothers careful not to drop behind. Not a syllable of complaint escaped his lips.
他慢吞吞地跟在哥哥们的后面，努力不被他们落下，但他一句抱怨的话都没说。
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