正方体$ABCD-A_1{B}_1{C}_1{D}_1$，棱长为2，点$A_1$到截面$A{B}_1{D}_1$的距离为(     )

***诗词《送瘟神》中“坐地日行八万里，巡天遥看一千河”所指的地区是（　　）

You Can Fly More Frequently

    When traveling, airfare can take up a large part of your travel budget. What if you could fly practically for free? If it were possible, then you would probably travel more, right?____ While it may seem like a lot of work to accumulate miles, it's pretty easy when you know how.

    Sign up for mileage (里程) programs. You can't gain miles if you don't sign up.____ Pick one or two airlines that you use most often and try to bring all your points into those programs by flying with them.

    Buy gifts and have dinner out. Most mileage programs have a business list where you can register several credit or debit cards and then earn miles for each purchase you make through their participating shops or meal you have at restaurant partners.____so why not make it count toward future travel?

    Use your credit card. Look for a card that gives you rewards. There are a ton of credit card companies that offer mileage cards that give you miles for each dollar you spend. Use it for bills, groceries, gas and anything else you would normally use your bank account for and then pay it off at the end of the month.____

    Rent a car. Whenever you rent a car, you have the choice to include your frequent flyer member number.____ but it can be more beneficial to pay less than a dollar a day to earn one or more miles per dollar spent on your rental.

A. Some will charge a fee

B. With frequent flyer programs, you can

C. You're probably doing these things anyway

D. It's an easy way to accumulate miles and can add up really fast

E. In fact, you can get a free plane ticket just focusing on certain ones

F. Join frequent flyer programs, so you can start accumulating those miles

G. There are plenty of ways to earn money just by doing things you're already doing