自2010年至今的四级考试中， 共出现过 次
自2010年至今的六级考试中， 共出现过 次
N-COUNT 钥匙 A key is a specially shaped piece of metal that you place in a lock and turn in order to open or lock a door, or to start or stop the engine of a vehicle.
They put the key in the door and entered...
She reached for her coat and car keys.
N-COUNT （计算机或打字机的）键 The keys on a computer keyboard or typewriter are the buttons that you press in order to operate it.
N-COUNT （钢琴或风琴的）键 The keys of a piano or organ are the long narrow pieces of wood or plastic that you press in order to play it.
N-VAR （音乐的）调 In music, a key is a scale of musical notes that starts on one specific note.
...the key of A minor.
N-COUNT （地图、图解或科技书籍的）略语表，符号表，凡例 The key on a map or diagram or in a technical book is a list of the symbols or abbreviations used and their meanings.
You will find a key at the front of the book.
ADJ 最重要的；关键的 The key person or thing in a group is the most important one.
He is expected to be the key witness at the trial...
Education is likely to be a key issue in the next election.
N-COUNT 关键；要诀 The key to a desirable situation or result is the way in which it can be achieved.
The key to success is to be ready from the start...
Diet and relaxation are two important keys to good health.