当x=-1是，x+1=0，
即当分式的分母是（x+1）时，该分式无意义．
故选C．
His sister has recently got engaged ____ a foreign teacher, who has engaged ____ education research for years.
A．with; in
B．to; in
C．with; on
D．in; for
白芷善治的是
A．太阳头痛B．阳明头痛C．少阳头痛D．厥阴头痛E．少阴头痛
