once用法oncewereceivethenews,we'lltryourbesttohelpyou.不能用receiving么,为什么?oncereceivingthenews,we'lltryourbesttohelpyou.这个句子不对么?必须要是介词比如after才能在后面直接加ing么?也就是说这

Question

once用法once we receive the news,we'll try our best to help you.不能用receiving么,为什么?
once receiving the news,we'll try our best to help you.这个句子不对么?必须要是介词比如after才能在后面直接加ing么?也就是说这个不是省略句,省略的话必须省略主语加be么?请分条回答,

Answer 1

"Once" receiving ...不允许; "Once we receive your reply to our setup email,our staff will create your Moodle course(s),and assign your user account.../I will give you full details once I receive your response./

"After receiving..." 就可以...After receiving your response,i sent the following emails/letters...

"We look forward to receiving your reply” 句子对!