在生物圈的碳一氧循环中，能使二氧化碳进入生物体中（形成为有机物）．又能将其释放到大气中的生物是（ ）
A．细菌
B．真菌
C．动物
D．绿色植物
答案：D
拔牙后出现口腔上颌窦瘘，但穿孔不大时
A．必须做瘘口修补术
B．使拔牙创内充满血块
C．冲洗拔牙创
D．填塞明胶海绵
E．行上颌窦根治
—I didn't go to class last night because my car broke down.
—You mine. I wasn't using it.[ ]
A. should borrow
B. might have borrowed
C. could have borrowed
D. must have borrowed
