performative verbs

He seems to be a great athlete = It seems that he is ... 他好像是个了不起的运动员。（他现在是）

He seems to have been a great athlete. (= It seems that he was ...) 他好像曾经是个了不起的运动员。(他过去是……)

在你问的句子里, to have caused the fire 所表达的动作发生在 appeared 之前。如果把它改成 to cause the fire, 则动词不定式 to cause 所表达的动作与谓语动词所表达的动作同时发生或在它之后发生, 那就不符合句意和上下文了。

请注意下列各句中动词不定式完成式的含义：

1. I appear to have made a small mistake. 我好像犯了个小小的错误。

2. They seemed to have disappeared. 他们似乎消失了。

3. Someone seems to have stolen the computer. 似乎有人偷走了那台计算机。

4. You appear to have travelled quite a lot. 你好像旅游了许多地方。

5. I don't appear to have written down his name. 我似乎没有写下他的名字。

[附注]动词不定式的完成式在某些动词之后充当宾语时，并不表示它所表达的动作在谓语动词所表达的动作之前业已完成，而是表示本想(计划、打算)完成，而实际上并未完成，见 $\mathrm{<span\; class="latin-run">e</span>}\mathrm{<span\; class="latin-run">x</span>}\mathrm{<span\; class="latin-run">p</span>}\mathrm{<span\; class="latin-run">e</span>}\mathrm{<span\; class="latin-run">c</span>}{\mathrm{<span\; class="latin-run">t</span>}}^5$expect^{5} ， $\mathrm{<span\; class="latin-run">h</span>}\mathrm{<span\; class="latin-run">o</span>}\mathrm{<span\; class="latin-run">p</span>}\mathrm{<span\; class="latin-run">e</span>}(\mathrm{<span\; class="latin-run">v</span>}\mathrm{.}{)}^5$hope(v.)^{5} ， $\mathrm{<span\; class="latin-run">m</span>}\mathrm{<span\; class="latin-run">e</span>}\mathrm{<span\; class="latin-run">a</span>}{\mathrm{<span\; class="latin-run">n</span>}}^9$mean^{9} ，would love to have done, intended to do, suppose $^{5}$ 。在 should 和 ought to 等情态动词之后的动词不定式完成式也表示实际并未完成，见 should have done, ought to have done。

在 expect, hope, 'd better 等动词的一般现在时之后的动词不定式的完成式并不表示它们所表达的动作在谓语动词所表达的动作之前完成,而是在此之后完成(强调完成性):

1. He expects/hopes to have finished by June. 他预料/希望在六月份之前干完。

2. You'd better have finished by tomorrow. 你最好明天干完。

(参见 infinitive $^{16}$ )