Cho biểu thức:
P = \(\left(2+\frac{a+\sqrt{a}}{\sqrt{a}+1}\right)\left(2-\frac{a-\sqrt{a}}{\sqrt{a}-1}\right)\)
a) Tìm điều kiện xác định của P.
b) Rút gọn biểu thức P
c) Với giá trị nào của a thì P có giá trị bằng \(\sqrt{\frac{\sqrt{2}-1}{1+\sqrt{2}}}\)
13. The teacher asked his students where did they put his pen, but no answers
A B C
were returned.
D
14. Mrs. Lien has taught English at my old school since such a long time.
A B C D
15. It’s been two years since I last met my parents. I have seen them since then.
A B C D
16. These are your old casettes which Sarah wants to borrow, aren’t these?
A B C D