下列说法正确的是( )
A．若直线l1与l2斜率相等，则l1∥l2
B．若直线l1∥l2，则k1=k2,
C．若直线l1,l2的斜率不存在，则l1∥l2
D．若两条直线的斜率不相等，则两直线不平行
答案：D
l1与l2斜率相等，l1和l2可能重合，故A错；l1∥l2时，它们有可能都不存在斜率，故B错；l1、l2斜率不存在时，l1，l2可能重合，故C错.
| 从方框中选择适当的句子完成对话，有两个多余选项。 | |
| A: Hello, Ben. Do you want to know my morning? B: __1__ What time do you usually get up? A: __2__ B: Oh, it's quite (很) early (早的). __3__ A: I usually get to school at seven-forty. B: Does school start at eight-thirty? A: __4__ It starts at eight o'clock. B: __5__ A: I usually eat lunch at school. And I often play soccer after lunch. B: Great. I like playing ping-pong, too.
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