She ____ homework when I arrived. [ ]
A. does
B. is doing
C. did
D. was doing
答案:D
食物过敏(foodallergy,FA)是由特殊食物蛋白引起的异常或过强的免疫反应。
食物过敏的易感年龄是()
A.学龄前期
B.婴儿期
C.幼儿期
D.新生儿期
E.学龄期
采用种植隔热屋面时,屋面坡度不宜大于()。
A.1%;
B.2%;
C.3%;
D.5%;