1. 不计算，在$\bigcirc$里填上“＞”、“＜”或“=”。
$15\times\frac{3}{5}\bigcirc15$ $1.5\times1.1\bigcirc1.1$ $\frac{3}{4}+\frac{2}{5}\bigcirc\frac{3}{4}\times\frac{2}{5}$
$15\div\frac{3}{5}\bigcirc15$ $0.9\div0.01\bigcirc0.9$ $0.1\times10\bigcirc10\div0.1$

2. $18\times\frac{5}{6}=$ $10\div\frac{5}{9}=$ $\frac{3}{4}\times12=$ $3 - 3\div4=$
$\frac{5}{9}\div3=$ $\frac{2}{3}\div\frac{3}{2}=$ $12\div\frac{3}{4}=$ $\frac{2}{5}+\frac{3}{5}\div\frac{1}{2}=$
$\frac{7}{10}\times\frac{5}{21}=$ $\frac{4}{5}\div4=$ $\frac{5}{7}+\frac{6}{7}=$ $(\frac{5}{6}-\frac{2}{3})\times12=$

3. 计算下面各题。
$4\times\frac{4}{5}$ $(\frac{4}{7}-\frac{5}{21})\times42$ $\frac{5}{16}\div\frac{3}{4}$
$3\div\frac{3}{4}\times\frac{3}{4}\div3$ $99\div4+\frac{1}{4}$ $\frac{7}{10}\times15\div\frac{7}{100}$
$\frac{4}{7}+\frac{4}{7}\div\frac{4}{7}$ $\frac{3}{5}\times\frac{10}{27}\times\frac{9}{14}$ $\frac{4}{5}+\frac{4}{9}\times\frac{5}{9}$

4. 在$\bigcirc$里填上“＞”、“＜”或“=”。$(a,b$均不为零$)$
(1) $a\times\frac{3}{8}=b\times\frac{3}{5}$ $a\bigcirc b$ (2) $a\div\frac{3}{8}=b\div\frac{3}{5}$ $a\bigcirc b$
(3) $a\times\frac{3}{8}=b\div\frac{3}{8}$ $a\bigcirc b$ (4) $\frac{3}{8}\div a=\frac{3}{5}\div b$ $a\bigcirc b$