Could you stand _________ for me and teach my English class tomorrow morning, John?

A. up                    

B. down               

C. out 

D. in

She must have been sleepless last night. Otherwise, her eyes _______ so bloody now

A. won’t look

B. wouldn’t look

C. wouldn’t have looked

D. looked

If she had accepted his proposal, she __________now.

A. would have been married                          

B. is married

C. has been married                                       

D. would be married

Chất có thể dùng để làm mềm nước có tính cứng toàn phần là

A. Na₃PO₄. 

B. CaCl₂.    

C. HCl.       

D. NaHSO₄

\(5^x+5^{x+2}=650;5^x.26=650;5^x=25;x=2\)

\(2^x+2^{x+3}=144;2^x.9=144;2^x=16;x=4\)

\(3^{x-1}+5.3^{x-1}=162;3^{x-1}.6=162;3^{x-1}=27;x=4\)

\(\left(x-5\right)^4=\left(x-5\right)^6\)

\(\rightarrow x-5=0\&x-5=1\) hoặc x - 5 = - 1

\(x-5=1;x=6;x-5=0;x=5;x-5=-1;x=4\)

\(\left(2^2:4\right).2^n=4;2^n=2^2;n=2\)