Question $3(20$ points$)$

Select all the correct statements:

$\underset{x0}{lim}\frac{1+x+sinx}{x+2cosx}=\frac{1}{2}$

$\underset{x0}{lim}\frac{x^2+x+7}{2x+2}=\underset{x0}{lim}\frac{2x+1}{2}=\frac{1}{2}$

$\underset{\frac{}{2}}{lim}\frac{2-2sin}{1+cos2}=\frac{1}{2}$

$\underset{t0}{lim}\frac{sint}{e^{2t}-1}=\frac{1}{2}$