Có bao nhiêu cách sắp xếp 10 người vào 10 chỗ ngồi được sắp cách đều nhau bên bàn tròn mà em bé ngồi cạnh và giữa hai vợ chồng (trong 10 người thì có 2 vợ chồng và 1 em bé)? 

A. 3.7!

B. 9!

C. 3!.7!

D. 2.7! 

Một chiếc hộp đựng 6 cái bút màu xanh, 6 cái bút màu đen, 5 cái bút màu tím và 3 cái bút màu đỏ được đánh số từ 1 đến 20. Lấy ngẫu nhiên ra 4 cái bút. Tính xác suất để lấy được ít nhất 2 bút cùng màu.

A. 311 323

B.  123 323

C.  287 323

D.  237 323

Tập xác định của hàm số  y = 1 - cos x sin x - 1  là

A.  ℝ \ π 2 + k 2 π

B. ℝ \ π 2 + k π

C. ℝ \ k 2 π

D. ℝ \ k π

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.

To many people, their friends are the most important things in their life. Really good friends (1)___ the good times and the bad times, help you when you have got problems and never turn their backs on you. Your best friend may be someone you have known all your life, someone you have grown up with and been through lots of (2)_____ and downs with.

There are all sorts of things that can (3)______ about this special relationship. It may be the result of enjoying the same activities, having the outlook on life or sharing experiences. Most of us have met someone that we have immediately felt relaxed with as if we had known them for years. (4)_______, it really takes you years to get to know someone well enough to consider your best friend.

To the majority of us, this is someone we trust completely and who understands us better (5)______ anyone else. It is the person you can turn to for impartial advice and a shoulder to cry on when life gets you down.

Question 4.

A. Because

B. Although

C. Otherwise

D. However