问题 选择题

下列物质中一定含有氢元素,可能含有氧元素的是(  )

①酸②酸式盐③碱④碱式盐⑤碱性氧化物.

A.①②

B.①②③④

C.②④

D.①②④

答案

①酸中含有氢离子,所以酸中一定含有氢元素,酸分为含氧酸和无氧酸,含氧酸中一定含有氧元素而无氧酸中不含有氧元素,所以可能含有氧元素;故符合

②酸式盐中除金属离子和酸根离子之外还含有氢离子,所以酸式盐中一定含有氢元素;含氧酸盐中一定含有氧元素而无氧酸盐中不含有氧元素,所以可能含有氧元素;故符合

③碱中含有氢氧根离子,所以碱中一定含有氢、氧元素.故不符合

④碱式盐中除金属离子和酸根离子之外还含有氢氧根离子,所以碱式盐中一定含有氢、氧元素.故不符合

⑤氧化物中一定含有氧元素,不含有氢元素;故不符合

故选A

问答题 简答题
单项选择题

You know you should do it, other people do it all the time. Maybe you’ve already done it but it wasn’t very satisfying, and you’d like to learn to do it better.

I’m talking, of course, about having a business lunch.

Don’t feel embarrassed if you are uncomfortable with the idea of sitting over a grilled chicken breast, talking to a prospective client.

Most inexperienced, overeager launchers believe the main purpose of a business lunch is to either (a) conduct business or (b) eat lunch, and they’re unsure how to mix the two. Don’t worry! Business lunches aren’t about either business or lunch,

they’re about building relationships.

One of my business rules is "People do business with people they like. "

Often, it’s not products, prices, or the company that makes the sale—it’s the person Business lunches are the perfect time for you and your client, supplier, or employee to get to know each other as people. This helps establish common interests and makes working together easier.

The single most important thing you can do at a business lunch—even more important than picking up the tab—is listen.

You don’t need a particular reason to ask someone to lunch, so don’t wait until for a certain occasion or issue.

Don’t make it seem like lunch is going to be a sales call. Instead, try the straightforward approach, "We’ve been doing business together for almost a year. I’d like to take you to lunch and get to know you a little better." Or a little less straightforward, "I’m often in your area, how about having lunch sometime"

Have the other person suggest a place to eat—"Is there a restaurant you’ve been wanting to try" Or if you have a limited budget, you choose a nice mid priced restaurant. Forget McDonald’s. If you’re thanking someone for an important order, take them to a really special, possibly new, restaurant.

If you did the inviting, you pick up the tab, even if your guest says, "I can put this on my company’s credit card." But don’t have a scene arguing over the check. You can just say, "You can get the next one." Some companies have policies that don’t permit employees to be treated; in that case, split the tab.

According to the passage, a successful businessman should know()

A. how to offer to pay for a business lunch

B. what kind of food is nice, yet inexpensive

C. how to make friends with clients

D. which restaurants offer nice food