18: 2 Page, ABE plane corresponds to EF, BD and AC respectively, and is derived from the last two cubes.
Step 3 draw it yourself
4. It consists of at least six cubes.
Page 19: 1, which is surrounded by four faces, the faces intersect with six straight lines, and the straight lines intersect with curves.
2 1 ratio 3, 2 to 2, 3 to 1
3. The first one can't be a prism, the second one can be a triangular prism and the third one can't be a prism.
4. They are heptagon, rectangle, trapezoid and rectangle respectively.
5, can be rectangular and square.
6, subtract the third square in the second column.
7. Draw it yourself
8, ditto
9,7-4 = 3m6 divided by 2=3M.
3. 14 times the square of 3 times 1/3 times 3 =28.26 cubic meters.
Cubic quadratic 3. 14 times 4= 1 13.04 cubic meters.
28.26+113.04 =141.3 m3.
10, which can be an inverted triangle, quadrilateral or pentagon.
1 1, irregular figure
Page 25: 1, (1) is marked as -3 degrees Celsius (2), moving 2 cm to the east, and the stationary mark is 0.
(3), recorded as-3.8t..
2, a set of positive numbers: 3, 5.6, 15, one ninth.
A set of negative numbers: -7, -2/3, -8 and 1/4.
Integer set: 0, 3, -7, 15
Score setting:-two thirds,-eight and a quarter, one ninth, 5.6.