He has played soccer since three o’clock.

=>He started ................................................................................................................................................ 

They planted this tree last year.

=>This tree ........................................................................................................................................

to use/ If we/,/ we/ the water/ won’t have/ fresh water / pollute.

=>

You must finish this exercise before 4 o’clock.

=>This exercise ...........................................................................................................................................

were/ Corona virus/ there/ no/ If only/.

=>

last / a serious flood / was/ There/ year/ in this area/.

=>

Tìm x

\(\sqrt{\left(x-3\right)^2}-7=0\)

Rút gọn 

C=\(\dfrac{\sqrt{x}+1}{\sqrt{x}-2}+\dfrac{2\sqrt{x}}{\sqrt{x}+2}-\dfrac{2+5\sqrt{x}}{x-4}\)(với x≥0 , x ≠4)