Complete the text with one suitable modal verb in each space :

Some people always have good advice to give you, but only after the event. You (1).......... have come across the type, who somehow always know what you (2)........... have done when it has become too late. By now I (3).......... spot them a mile off. It (4)............ be because I have had so much practice. Last week, for example, I (5)............ to take my car to the garage because the lights weren't working. It was an expensive job, but I decided that I (6)........... as well pay, and get it over quickly. "You (7).............. have told me", said a friend when I was telling him how much I (8).............. to pay. "I (9)............ easily have fixed it for you. Then you (10)............... not have wasted so much money." You (11)............... imagine how I felt ! Actually, he (12)................. probably have made a mess of the job, and I (13)............... well have ended up paying more. But it does seem strange that everyone else (14)................ know exactly what I (15)............. to do.

Tks 4 helping ! Me in need now :v

\(2A=2^1+2^2+2^3+2^4+...+2^{2010}.\)

\(A=2A-A=2^{2010}-2^0=2^{2010}-1\)

=> A và B là 2 số tự nhiên liên tiếp