空间数据的拓扑关系主要包含哪几类？建立拓扑关系有何应用价值?
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1. My brother Sam doesn’t like sports. He ______ plays sports with friends.
A. often
B. usually
C. never
D. always
—What is Peter doing at 7:30 in the morning?—He __________ breakfast with his family.
A. is have
B. is having
C. has
D. are having
Sometimes Alice _______ a walk with her parents after supper.
A. takes
B. take
C. to take
D. is taking
My father _______busy at his work.
A. is always
B. does always
C. always is
D. alwaysdoes
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