1、( 1)× (2)× (3)√

2. (1) 3.14× (12 ÷ 2) 2×12 =1356.48 cubic centimeters.

(2)12×12-1356.48 = 371.52 cubic centimeters.

3, can form a conical object.

3.14× 82× 6×1/3 = 401.92 cubic centimeters.

4.( 1)25. 12÷3. 14÷2 = 4m。

3. 14× 42 = 50.24 square meters

(2) 50.24×1.8×1/3×1.35 = 40.6944 tons ≈4 1 ton.

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1 、( 1)C (2)A (3)C

2.( 1)3. 14×40×20 = 25 12 cm2

(2) 3.14× (40÷ 2) 2× 20 = 25120 cubic centimeter.

(3) 40× 4-20× 4-20 = 260 cm

3、(4- 1)×2=6

0.18 ÷ 6 = 0.03m2.

0.03× 2.4 = 0.072 cubic meters