Sắp xếp học sinh lớp và học sinh lớp vào hai dãy ghế đối diện nhau, mỗi dãy ghế sao cho học sinh ngồi đối diện nhau thì khác lớp. Khi đó số cách xếp là:

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Find a mistake in the four underlined parts of the sentence and correct it:

  A hurricane’s force begins to distinguish as soon as it will strike land.

• Find a mistake in the four underlined parts of the sentence and correct it:

  When he was telling them what had happened, they thought he was madder still.

• Find a mistake in the four underlined parts of the sentence and correct it:

  She has been waiting at the airport for over an hour before she finally received a message

  telling her to go direct to her hotel.

• Find a mistake in the four underlined parts of the sentence and correct it:

  After he made sure no one was waiting for him in the hotel lobby, he had collected his key

  at the reception desk.

• Find a mistake in the four underlined parts of the sentence and correct it:

  Jane was dropping a carton of eggs as she was leaving the room.

• Find a mistake in the four underlined parts of the sentence and correct it:

  After Nam will finish his degree, he intends to work in his father’s company.

• Find a mistake in the four underlined parts of the sentence and correct it:

  Class had already begun in the time I got there, so I quietly took a seat in the back. 

• Find a mistake in the four underlined parts of the sentence and correct it:

  My sister puts on a wig whenever she goes out, but I never wear a wig in my whole life.

• Find a mistake in the four underlined parts of the sentence and correct it:

  I admire Tom with his courage and honesty in admitting that mistake.

• Find a mistake in the four underlined parts of the sentence and correct it:

  The car park is free, so you mustn’t pay to park your car there.