$\text{Answer : }$
`41.` $\text{T}$
`42.`$\text{F}$
`43.`$\text{The environment is being polluted.}$
`44.`$\text{It is the responsibility of the whole humankind.}$
`45.`$\text{Because of being lazy, Lam did not finish his homework.}$
`46.`$\text{She last visited her grandparents 3 months ago .}$
`47.`$\text{That is Maryam whom Lan and Nga met last week.}$
`48.`$\text{Peter told me that he was going to speand his summer vacation in the countryside.}$
`49.`$\text{It takes him half an hour to walk to school every day.}$
`50.`$\text{My mother used to work hard on the farm when she was young}$
$\text{Good luck !}$
