问题 填空题
在下面的横线里填上合适的数.
(1)
5
7
×______=1;
(2)9×______=1;
(3)
7
12
×______=1;
(4)______×12=1;
(5)______×
1
18
=1

(6)______×
17
19
=1

(7)
1
2
×______=______×
1
3
=
1
4
×______=______×
1
5
答案

(1)

5
7
×
7
5
=1;

(2)9×

1
9
=1;

(3)

7
12
×
12
7
=1;

(4)

1
12
×12=1;

(5)18×

1
18
=1;

(6)

19
17
×
17
19
=1

(7)

1
2
×2=3×
1
3
=
1
4
×4=5×
1
5

故答案为:

7
5
1
9
12
7
1
12
;18;
19
17
;2,3,4,5.

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