Correct Answer: C.

Analysis: Sentence meaning: Professor Brown treated the students to dinner at a Mexican restaurant. at sb's expense Meaning: at someone's expense.

I. students

1. meaning: students.

2. Usage:

student in British English refers to "college students, college students", in American English can also mean "primary and secondary school students".

Student is often used in conjunction with of when it means "researcher, scholar".

This method can help students shed inhibitions.

II. entertained

1. Meaning: v. to entertain; to make interested; to entertain; to consider; to hold; to accommodate.

2. Usage:

The basic meaning of entertain is "to entertain", which means to make someone happy by providing a meal or a service or something else, and it can be extended to "(to make) happy". "(to) entertain".

entertain can be used as a transitive or intransitive verb. When used as a transitive verb, it can be followed by a pronoun or a noun as a simple object. It can be used in passive constructions.

We were all entertained by his humorous stories.

His humorous stories entertained us all.

Three, restaurant

1. Meaning: n. restaurant; restaurant.

2, Usage:

restaurant's basic meaning is "hotel" "restaurant", refers to the place for food and drink, small can refer to only a counter and a few tables of the small restaurant, large can refer to the availability of The term "restaurant" refers to a place where meals are served, from small restaurants with a counter and a few tables to large restaurants with seating or private rooms that sell a variety of foods or specialize in one country's flavor.

In terms of hours of operation, it can refer to those restaurants that have certain hours of operation and specialize in serving breakfast, lunch and dinner, as well as those that are open day and night and are ready to dine at any time.

There are many streamers in front of the restaurant.

There are many streamers in front of the restaurant.

4. Professor

1. Meaning: n. professor; teacher.

2, Usage:

professor in the United Kingdom refers to the "university professor", men and women; in the United States in the spoken language often refers to the male Mr. or Mr. teacher of both sexes.

Professor means "a professor at a school", in or at before the name of the school. in is a formal usage.

Our professor is a man of profound learning.

V. Expense

1. Meaning: n.? Expense; expense; cost.

2, Usage:

Entered the English language in the late 14th century, and is directly derived from the Modern Latin expensa, meaning to spend, consume, consume.

As a noun, it means "to spend, expense", whileense contains a more uncertain meaning, referring to "fee" and "expense" in general.

He finished the job at the expenses of his health.

He finished the job at the expense of his health.