单词	a serious problem
释义	a serious problem 重要的课题
随便看	planetary radiation planetary radiation budget planetary radiometer planetary reducer planetary reduction gear planetary reduction gear box planetary reflectance planetary remote sensing planetary reverse reduction gear planetary reversing gear planetary ring planetary rings Planetary Rocket Launcher Platform Planetary Rocket Ocean Platform planetary roiling planetary roller extruder planetary rolling planetary rolling mill planetary rolling stand planetary roll mill planetary rotating speed planetary rotation planetary rotation engine planetary rotation machine planetary rotation rate