十字接头
参考答案：
十字接头指一焊件与另两焊件装配成十字形的接头。
Health problems are closely connected with bad eating habits and a _____ of exercise. [ ]
A. amount
B. lack
C. need
D. number
一对单眼皮的父母，不可能生一个双眼皮的孩子．______．
