问题
选择题
Has someone suggested there _____ be an international language all could understand and use _____ ? [ ]
A. can;it
B. may;／
C. /; /,
D. would; it
答案
答案：C
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Has someone suggested there _____ be an international language all could understand and use _____ ? [ ]
A. can;it
B. may;／
C. /; /,
D. would; it
答案：C
(1) 若λ=0，则方程组有非零解； (2) 若λ=1，则方程组有非零解； (3) 若λ=-1，则方程组有非零解； (4) 若λ≠0且λ≠1，则方程组只有零解； 以上命题正确的个数为( )个．