下列观察、测量和实验操作中，正确的是（ ）
A：向试管中加固体
B：稀释浓硫酸
C：调节粗准焦螺旋使镜筒上升
D：测量正方体的边长
计算：1a-1-1a+1=____
Mr. Wang _____ gets up early. So he is ______ late for work.
It's a snowy day. Let's make a snowman. Let's make a big snowball for his ____, and a small snowball for his ____. Let's draw his ____. Let's put two sticks for his ____. Let's put a hat on him. I ____ he's wonderful!
