Mary has been a secretary in this company ______s

There is always the ____of an earthquake in this region, but so far there has been no sign

A considerable amount of time and money has been invested in ______ this system.A．defining

Mary says this is the______ decision she has ever made in her career life.A．badB．worstC．wo

In______, Chinatown has been the center of its Chinese community since the 1850s, which is

Mary looks unhappy because she has ______ by her classmates.A、laughedB、laughed atC、been

This book has been in the works so long that I have lost ______ of most of the sources fou