Chọn câu sai.

Đáp án A: Ta có:

$\dfrac{2}{{ - 3}} = \dfrac{{ - 2}}{3} = \dfrac{{ - 2.8}}{{3.8}} = \dfrac{{ - 16}}{{24}};$$\dfrac{{ - 7}}{8} = \dfrac{{ - 7.3}}{{8.3}} = \dfrac{{ - 21}}{{24}}$

Vì $\dfrac{{ - 16}}{{24}} > \dfrac{{ - 21}}{{24}}$ nên suy ra $\dfrac{2}{{ - 3}} > \,\,\,\dfrac{{ - 7}}{8}$ nên A đúng.

Đáp án B: Ta có:

$\dfrac{{ - 22}}{{33}} = \dfrac{{ - 22:11}}{{33:11}} = \dfrac{{ - 2}}{3};\,\,\,\,\,\,\,\,\,\dfrac{{200}}{{ - 300}} = \dfrac{{ - 200}}{{300}} = \dfrac{{ - 200:100}}{{300:100}} = \dfrac{{ - 2}}{3}$

Vì $\dfrac{{ - 2}}{3} = \dfrac{{ - 2}}{3}$ nên suy ra $\dfrac{{ - 22}}{{33}} = \dfrac{{200}}{{ - 300}}$ nên B đúng.

Đáp án C: Ta có:

$- \dfrac{2}{5} < 0\,;$$\dfrac{{196}}{{294}}\, > 0$$\Rightarrow \dfrac{{ - 2}}{5} < 0 < \dfrac{{196}}{{294}}$ $\Rightarrow \dfrac{{ - 2}}{5} < \,\,\,\dfrac{{196}}{{294}}$  nên C đúng.

Đáp án D: Ta có:

$\dfrac{{39}}{{ - 65}} = \dfrac{{39:( - 13)}}{{( - 65):( - 13)}} = \dfrac{{ - 3}}{5}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$

Vì $\dfrac{{ - 3}}{5} = \dfrac{{ - 3}}{5}$ nên suy ra $\dfrac{{ - 3}}{5} = \,\dfrac{{39}}{{ - 65}}$ nên D sai.