用法:
1 [Tn] change or spoil the colour of (sth) 使（某物）变色; 使（某物）退色:
Smoking discolours the teeth. 吸烟会使牙齿变色.

用法:
2 [I] (of colour) change or be spoilt （指颜色）变化, 变色, 退色.

• hard cash
• hard copy
• hard core
• hard court
• hard cover
• hard currency
• hard disk
• hard drug
• harden
• hard-headed
• hard-hearted
• hard-hitting
• hardiness
• hard labour
• hard-line
• hard-liner
• hardly
• hard-nosed
• hard porn
• hard-pressed
• hard sauce
• hardship
• hard shoulder
• hard-top
• hardware