YSK: A contract does not have to be physically written or signed for it to be legally binding. Even a verbal contract is legally enforceable if it can be proven.
from /r/YouShouldKnow
YSK：合同不一定非得是書面的或簽署的，才具有法律約束力。即使是口頭合同，如果能夠得到證明，也是具有法律效力的。
YSK：合同不一定非得是書面的或簽署的，才具有法律約束力。即使是口頭合同，如果能夠得到證明，也是具有法律效力的。
YSK: A contract does not have to be physically written or signed for it to be legally binding. Even a verbal contract is legally enforceable if it can be proven.
from /r/YouShouldKnow