Cho hình hộp ABCD.EFGH. Gọi I là tâm hình bình hành ABEF và K là tâm hình bình hành BCGF. Trong các khẳng định sau, khẳng định nào đúng?
A.  $\overrightarrow{{BD}},\overrightarrow{{AK}},\overrightarrow{{GF}}$ đồng phẳng.    
B.  $\overrightarrow{{BD}},\overrightarrow{{IK}},\overrightarrow{{GF}}$ đồng phẳng.
C.  $\overrightarrow{{BD}},\overrightarrow{{EK}},\overrightarrow{{GF}}$ đồng phẳng.   
D. Các khẳng định trên đều sai.

Cho hàm số $y=\frac{1}{\sqrt{\sin x+1}}.$ Tập xác định của hàm số là
A. $R\backslash \left\{ -\frac{\pi }{2}+k2\pi |k\in Z \right\}.$
B. $R\backslash \left\{ \frac{\pi }{2}+k2\pi |k\in Z \right\}.$
C. $R.$
D. ${{R}^{*}}.$

Choose the best answer for the following sentence:
A dry pass, meaning the ball does not ________________ the water is thrown a few inches above the head of the catching player.
 
A. catch             
B. hold              
C. swim                
D. touch

Choose the best answer for the following sentence:
Most people are __________ than their parents used to be. 
A. better off                    
B. the best off
C. as well off                    
D. best off

Choose the best answer for the following sentence:
Did __________________ happen? No, nothing happened. 
A. nothing                 
B. anything                    
C. any                
D.  a thing

Choose the best answer for the following sentence:
The school administration decided to hold some ________________  classes for weak
students who have difficulty learning.
 
A. private                      
B.  adult                    
C.  evaluating                 
D. remedial

Choose the best answer for the following sentence:
______________ I've cleaned it and polished it, it still doesn't look new. 
A. Despite                 
B. Although                       
C. While                   
D. But

Choose the best answer for the following sentence:
“Tony and Toby look so much alike.” “Yes. It’s difficult to distinguish one tw¡n ___________ another.'' 
A. to               
B. by  
C. for 
D. from

Choose the best answer for the following sentence:
You have to pay extra if you take too _____________________ with you. 
A. much luggages                 
B. many luggages 
C. much luggage                
D. many luggage

Cho tứ diện $\displaystyle ABCD$ có hai mặt$\displaystyle ABC$ và$\displaystyle ABD$ là các tam giác đều. Góc giữa$\displaystyle AB$ và$\displaystyle CD$ là?
A. $\displaystyle 120{}^\circ $.
B. $\displaystyle 60{}^\circ $ .
C. $\displaystyle 90{}^\circ $.
D. $\displaystyle 30{}^\circ $ .