A：铁丝在空气中燃烧，火星四射
B：白磷在空气中燃烧，产生白烟
C：木炭在空气中燃烧，生成二氧化碳
D：硫粉在空气中燃烧，产生蓝紫色火焰
You are supposed to ___________ smoking, ___________ you will get ill.
____
下列运算正确的是（ ）
—How is Nancy getting on with her lessons? —She won't catch up with others she studies harder.
