8V+E)n(Q'x7B Even the top students in our class can’t work out this problem. So it _____ be very difficult.;b/I6~1I*z6\(c4`,d.S*T:O/x)r2l:S8P0o0m1M3S.Z
A. may;b/I6~1I*z6\(c4`,d.S*T:O/x)r2l:S8P0o0m1M3S.Z
B. must;b/I6~1I*z6\(c4`,d.S*T:O/x)r2l:S8P0o0m1M3S.Z
C. can;b/I6~1I*z6\(c4`,d.S*T:O/x)r2l:S8P0o0m1M3S.Z
D. need;b/I6~1I*z6\(c4`,d.S*T:O/x)r2l:S8P0o0m1M3S.Z