rudimentary

adj. 初步的，未充分发展的

Rubicon, rubicund, rubric, ruby, ruby wedding, RUC, ruche, ruched, ruck, rucksack, ruckus, ructions, rudder, ruddily, ruddiness, ruddy, rude, rudely, rudeness, rudiment, rue, rueful, ruefully, ruefulness, ruff, ruffian, ruffle, rug, Rugby, Rugby League, Rugby Union, rugged, ruggedly, ruggedness, rugger, ruin, ruination, ruined, ruinous, rule,