单有几种读音

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读下列各组单词，判断各组单词划线部分有几种读音。 A. 一种读音 B. 两种读音 C. 三种读音 D. 四种读音

( )1. pilot single machine April

( )2. engineer athlete sentence garden

( )3. resolution question station examination

( )4. retire fire tired wire

( )5. build June cup student