There are many ways you can save money at the supermarket . Here are some of the best:

    Make a list and follow it.

    The list is about your needs: the notebooks you're out of and the food you need for daily meals. When you buy the things that are not on the list, you are wasting your money.

    Compare the prices.

    The biggest package isn't always the cheapest. Sometimes it is cheaper to buy in bulk*. So it's useful for you to compare the prices.

    Ditch the basket or cart.

    If you're going to the supermarket just to pick up milk and bread, don't use a basket. Baskets let people to buy more. Only use a basket or a shopping cart if it's really necessary.

    Make one large trip instead of several small ones.

    Each time you enter the supermarket, you get another chance to spend. By reducing the times of your trips, you're saving both time and money.

    Shop when you are full.

    If you go to the supermarket for milk on a Sunday morning without eating breakfast, you are likely to come home with bread, sandwiches and orange juice.

苯的同系物中，有的侧链能被酸性高锰酸钾溶液氧化，生成芳香酸，反应如下：

(R，R′表示烷基或氢原子)

近亲结婚所生子女一定患遗传病。                              （     ）

原始大气中不含有（　　）