短文填空

It was late last Monday, but Tom was still ____ TV in his room. There was a wonderful football match on TV. ____  excited he was! That night he  ____ go to bed until twelve o'clock. The next morning, it was a quarter to eight. It was ____ late for Tom to get to school ____ time. But he was still in bed. When Tom ____ school, it was eight. The teacher was already beginning her lesson. As soon as Tom came into the classroom, she got  ____ and said,"What time is it now, Tom "Tom felt sorry and could say  ____ . In English class, he  ____ a test. As he didn't know the lessons at  ____ , Tom failed his English test.

在式子$\frac{1}{a}$、$\frac{2xy}{\mathrm{\pi }}$、$\frac{3a^2{b}^{3}c}{4}$、$\frac{5}{6+x}$、$\frac{x}{7}+\frac{y}{8}$、$9x+\frac{10}{y}$中，分式的个数有（     ）