等比数列{a_n}的各项均为正数，且a₂=2,a₄=$\frac{1}{2}$．

（Ⅰ）求数列{a_n}的通项公式；

（Ⅱ）设b_n=log₂a_n，求数列{b_n}的前n项和T_n．

①在下面直线上的相应位置标出 ，表示出496500。

②496500≈    万。

    It is interesting to visit another country, but there are some problems when we don't know the 1very well.It may be 2 to talk with the people there. We may not know how to use the telephone in the country that we are visiting. We may not know how to buy 3 we need. In a4country we might not know where to eat or what to order in a 5 It is not easy to decide how6to tip (给……小费) waiters or taxi drivers. When we need help, we might not know how to ask for help.It is not pleasant to have an experience7that. 8a short time, however, we learn what to do and what to 9We learn to enjoy life in another country and then we may feel 10 because we have to leave.