formal invitation

基本解释

A: So far as I know, we haven't received any formal invitation, therefore I can not predict or judge whether to accept or not.
答：根据我目前掌握的情况，我们还没有收到任何正式的邀请，无法预测或判断是否会接受。
www.fmprc.gov.cn
"Each student will receive a formal invitation to which he will have to respond in a written formal manner and not by email, text message or phone," the spokesman said.
这位发言人说：“每名学生都会收到一封正式邀请函，而他们必须以正式的书面形式答复，不得发电子邮件、发短信或打电话。”
In January he was dispatched to Libya to deliver a formal invitation for Muammar Qaddafi to visit Sri Lanka, to improve the “strong personal relationship” between the two country’s leaders.
一月，为了增强两国领导人之间“深厚的人际关系”，他奉命到利比亚正式邀请穆阿迈尔·卡扎菲总统到斯里兰卡访问。

"So far,at this date and time, I have no information if we have received any formal invitation from the organizers of that Hague summit,".
"But if we receive that formal invitation, we would consider that positively."

Such a formal invitation to foreign workers has not been known since the first Turks, then and still needed, but now so often unwelcome, arrived in the 1960s.
ECONOMIST: Europe’s migrants