There were/ funny trains/ some/ yaers ago/ one hundred

There weren't/ motorcycles / one hundred / any / years a go.

Last Saturdays / there wasn't /a / at the party/ cd plAyer.

Lost of /were/ there / twenty Years a go / buses

Didn't / go / they / shool/ to.

In the middle of / there / some lemons / the table / were

Between / there / the bus and the train / a motorcycle /wasn't

Inside / thetr / was/_a student/ the plane

At the top of / live/ a / my grandparents /_hill

rút gọn biểu thức

\(\dfrac{1}{31}+\dfrac{1}{32}+\dfrac{1}{33}+...+\dfrac{1}{89}+\dfrac{1}{90}\)