若a+b+c≠0，b+ca=c+ab=a+bc=k，则k=______．_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题填空题

若a+b+c≠0，

b+c

a

=

c+a

b

=

a+b

c

=k，则k=______．

答案

∵

b+c

a

=

c+a

b

=

a+b

c

=k，a+b+c≠0

∴k=

2(a+b+c)

a+b+c

=2．

故答案为：2．

选择题

We can______ about Chinese history from these doumentaries. [ ]

A. learn

B. to learn

C. learns

D. learning

名词解释

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