Rex soon became an expert at opening the gate,at后可以用不定式吗?为什么用-ing

Rex soon became an expert at opening the gate,at后可以用不定式吗?为什么用-ing become an expert at 与become expert at 与在新概念第二册的Lesson 59与Lesson 94中出现了,Rex soon became an expert at opening the gate与children become expert at holding their breath under water even before they can walk.其中expert前 请分析下这两个英语句子的成分I spent two weeks in reading this book.请问 this book在句子中是作reading的宾语补足语吗?Rex soon became an expert at opening the gate.请问opening是动名词还是现在分词,作什么成分, soon became an expert at opening the gate 句型转换soon （） （） （ ）opening the gate soon became an expert at opening the gate 句 型转换soon （） （） （ ）opening the gate 同义句转换:Daniel will send you an e-mail soon.Daniel will()()()()()soon. soon he became very interested in science soon he became very interested in science 英语翻译4.they soon became dood friends. I will send you an e-mail soon.同意句I will _____an e-mail______ you soon. basketball soon became very popular为什么soon要用在became前面 An old woman suddenly became rex是什么意思 REX怎么样 Rex是什么意思? Please send me an e-mail soon的同义句谢谢为了明天考试准备 I will send you an e-mail as soon as I___(arrive)in Hong Kong. tyrannosaurus rex中的rex是什么意思?