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The scientists were waiting to see the problem                      .   

A. settle              B. settled              C. to settle             D. settling

The scientists were waiting to see the problem _______.

　A. settle　　　               B. settled　　　           C. to settle　                     D. settling

The scientists were waiting to see the problem _______.

　A. settle　　　               B. settled　　　           C. to settle　                     D. settling

 The scientists were waiting to see the problem ____ 　.　
　 A. settle　　　         B. settled　　　         C. to settle　　　         D. settling

The scientists were waiting to see the problem ____ 　.　

A. set   　　　　　 B. settled　　　　 C. to settle　　　　  D. settling