A-level物理简答题答非所问怎么破？

A-level物理简答题看起来复杂多变，让人感到一头雾水，无所适从。但实际上，做这类题有一定的方法和技巧，只要熟练掌握，很多文字叙述题都可以迎刃而解。

在这类题中经常会出现一些关键词(command words)，比如，”Define”, “State”, “Compare”, “Describe”等。

大纲中对这些Command words给出了明确的定义与描述，告诉学生该如何回答这类问题。

在这里，我们总结经常出现的command words，帮助大家”拿下”这些纸老虎。

State/Define:

A formal statement is required or, if you give the defining equation, all terms in the equation must be explained. Where a ratio is involved, the ratio must be made clear. For example, density is mass per unit volume, not mass of unit volume. When defining a quantity, this should not be done in terms of units.

我们看到State/Define的简答题，虽然要求给出formal statement, 但是如果你给的是defining equation也一样拿分。我的天，终于不用背这么长的英文定义了。

Compare:

it requires candidates to provide both similarities and differences between things or concepts.

也就是说，对于”Compare”的简答题，我们需要明确的给出”similarities”和“differences“。看，是不是很容易就拿到分了。

Describe：

Set out the facts or characteristics. The description of a process should address what happens, and when and/or where it happens.

“Describe”类的简答题，也是比较容易丢分的题。对于这类题，我们需要强调两点点:”what happens”和“when/ where it happens”。

举例说明：

首先, what happens ：alternating p.d. is applied, magnetic field changes, alternating p.d. is induced.

其次, when/where it happens:在这里，我们需要指出”where it happens”。Magnetic field 是在iron core里变化，the induced p.d. 存在于 secondary coil。

最后，我们将这些点串起来：alternating p.d. applied in the primary coil causes the changing magnetic field, which induces alternating p.d. in the secondary coil. 对比给出的答案，我们很容易拿到了full mark。

explain:

Set out reasons and/or mechanismsto address why and/or how something happens.

For example, when asked to explain the change in rate of reaction seen on a graph, the expectedresponse would suggest scientific reasonsfor any change seen, for example in terms of molecular collisions or enzymatic action.

对于需要explain的题目，我们需要就题干中发生的事情，给出物理机制或者原因。

Give:a short answer is required without explanation.