—You’re coughing badly，Martin. Why not give up smoking?

—Give up smoking？Easier said than done，Amy. Once you ______ the habit of smoking，it is very hard for you to ______.

A．keep up; break it away

B．take up; drop it out

C．pick up; get rid of it

D．build up; do away with it

商业企业采取分期付款方式购进的商品用于对外投资，应视同销售货物征收增值税。