be difficult to do的不定式表被動(dòng)

類似于 be difficult to do 結(jié)構(gòu)中，若主語與其后的不定式為動(dòng)賓關(guān)系，那么該不定式習(xí)慣上要用主動(dòng)形式表示被動(dòng)意義。如：

She was difficult to understand at times. 有時(shí)候她很不容易理解。

能用于此結(jié)構(gòu)的形容詞主要有convenient, dangerous, difficult, easy, hard, impossible, interesting, nice, pleasant, safe, unpleasant 等。這類結(jié)構(gòu)的特點(diǎn)是句子主語必須其后不定式的邏輯賓語。如：

The poem is easy to understand. 這首詩容易理解。

Your writing is impossible to read. 你的書寫沒法認(rèn)。

He is hard to get along with. 他這個(gè)人很難相處。