Aliens are borrowed words which have retained their original pro

Aliens are borrowed words which have retained their original pronunciation and spelling. Which of the following words belongs to aliens?
A、kowtow
B、port
C、mother tongue
D、long time no see
【正确答案】：A
【题目解析】：外来词是外来词，它们保留了原来的发音和拼写。磕头属于外来词。