计算：cos30°﹣sin60°=____．

下列说法错误的是（　　）

    Teachers say buying homework answers online is not many in schools, but an interview with school students shows only 10% are willing to finish their holiday homework by themselves.
    Their main complaint is that the homework is too much for them to finish.
    “As far as I know, many of my students have to go to all kinds of training classes during the holiday. These take away much of their time for doing homework.”
    But as for the parents  who are sending their children to these training classes  they also say they've got no choice. Here's a view from a student's father.
    "All the other kids in the neighborhood are learning extra things. You know parents sometimes compare their kids. I'm afraid my kid will be less successful than the others in the future."
    In order to do with this situation of students copying each other's homework, some schools have even dropped the idea of holiday homework. Instead, they organize some interesting outdoor activities.
     Educational experts say students love to learn through games or activities that they can be a part of. They suggest schools drop the current (目前的）homework format (设计)，and turn to homework that encourages kids to get involved (参与).This way, they would no longer want to copy from each other or buy answers through the Internet.
    Answer the following questions according to what you read.

Tomorrow we'll go to the city park _____ it is sunny.  

    Restaurant  owners  have to know how  ____  ( make) food. They also have to know how to make money. Here are some things they ____ (learn) from scientific studies. The color red ____ (make) people hungry. Red also makes customers____ (eat) fast food restaurants, therefore, have red furniture or walls. Soft colors like pink and light blue make people____  ( relax), so they spend more time____ (eat) their meals. Soft lighting____  ( make )people look good, but it makes food look bad. Loud music  makes people want____ (  leave). Hard seats also____ ( make ) customers want to eat quickly and leave. Many restaurants, especially fast food restaurants, use this knowledge ____ (make) customers eat faster.