Dear Jenny,

    Now we are in the hospital of our city . My mother and I have a bad cold . We sees many children here . Some people have a cold. Some people have a headache. Some people have a fever. They a re waiting outside the doctor's room .Now it's our turn.

Yours,

Jack

$\sqrt{3x-6}$若在实数范围内有意义，则x的取值范围是（　　）