A.用电烙铁焊接电子元器件时,电烙铁要充分预热,烙铁头带上适量焊锡 |
B.使用台钻钻孔时要戴防护眼镜,以防碎屑伤害眼睛,可以佩戴手套防止手被擦伤 |
C.用手锯锯割金属,起锯时不能用拇指来定位,防止锯条滑动锯伤手指 |
D.锉削金属平面时,在推锉过程中要保持锉刀平稳,不上下摆动 |

同类型试题

y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2


y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2

