Can you tell me what you __________ when the teacher came into the classroom?
A：did
B：do
C：are doing
D：were doing
“留恋戏蝶时时舞，自在娇莺恰恰啼”描述了春天的美景。诗中蝶与莺的呼吸器官分别是（ ）
它是黄色的。可以说：
—It's ________unhealthy habit. Breakfast is very important to health.
