一、口算。
$7.5× 10\% =$
$\frac{5}{6}× 0.3 =$
$\frac{9}{10} + 99× \frac{9}{10} =$
$\frac{3}{7}× \frac{1}{18} =$
$1.01 + 9\% =$
$1 - \frac{1}{6} - \frac{1}{3} =$
$\frac{9}{20}× \frac{5}{18} =$
$\frac{4}{5}÷ \frac{16}{15} =$
$\frac{2}{3}× \frac{9}{4}× \frac{1}{2} =$
$2÷ 2\% =$
$\frac{7}{8}× 0.32 =$
$\frac{2}{3}× 2÷ \frac{2}{3}× 2 =$
$25\% × \frac{2}{3} =$
$\frac{4}{15}÷ \frac{8}{35} =$
$( \frac{3}{8} + \frac{3}{4} )× 4 =$
$\frac{5}{8} - \frac{2}{5} =$
$77\% + 33\% =$
$\frac{1}{4} + \frac{3}{4}× 4 =$
$7÷ 14\% =$
$\frac{17}{20} + \frac{2}{3} =$
$\frac{1}{3}÷ ( 2÷ \frac{1}{3} ) =$

1.$0.75$ 2.$\frac{1}{4}$ 3.$90$ 4.$\frac{1}{42}$ 5.$1.1$ 6.$\frac{1}{2}$ 7.$\frac{1}{8}$ 8.$\frac{3}{4}$ 9.$\frac{3}{4}$ 10.$100$ 11.$0.28$ 12.$4$ 13.$\frac{1}{6}$ 14.$\frac{7}{6}$ 15.$\frac{9}{2}$ 16.$\frac{9}{40}$ 17.$1.1$ 18.$3\frac{1}{4}$ 19.$50$ 20.$\frac{91}{60}$ 21.$\frac{1}{18}$

二、计算下面各图形中涂色部分的面积。
1.
2.

1. $3.14×(12÷2)^2÷2-3.14×(12÷2÷2)^2=28.26(\mathrm{cm}^2)$
2. $3.14×(20÷2)^2-3.14×(20÷2÷2)^2×2=157(\mathrm{cm}^2)$