There is invitation on the deskinvitation is from Lucy.A. an; AnB. the; AnC. an; TheD.

问题补充：

There is invitation on the desk. invitation is from Lucy.

A. an; An

B. the; An

C. an; The

D. the; The

答案：

A. an; An

B. the; An

(答案→)C. an; The

D. the; The

解析：桌子上有一个请柬。这个请柬是露西送的。结合语境可知前文泛指任何一份请柬，后面单词invitation词首音素是元音，故不定冠词用an。下文是特指前文桌子上的这个请柬，故用定冠词the。选C。