Translation

• key (on a piano or computer keyboard)
• button (on a mouse or other device)
• chemical bond
• linchpin

Examples

• 这个合夥事业成功的机会是很大的，关键就在于妳是否愿意努力、付出而
  This opportunity for success in forming a partnership is a big one; the key lies in whether you are willing to work hard and invest in it, and that is all.