灯具重量超过3公斤应预埋()或()固定。
参考答案:吊钩、螺栓
果蝇的红眼为伴X显性遗传,其隐性性状为白眼,在下列杂交组合中,通过眼色可直接判断子代果蝇性别的一组是 [ ]
A.杂合红眼雌果蝇×红眼雄果蝇
B.白眼雌果蝇×红眼雄果蝇
C.杂合红眼雌果蝇×白眼雄果蝇
D.白眼雌果蝇×白眼雄果蝇
The pupils hurried to the classroom______ the bell rang.
A.until
B.as soon as
C.if
D.so that