public boolean surrenderOne() {
		if (this.rentAmount > rentLimit ) {
			--this.rentAmount;
			++this.amount;
			// ָ״̬
			if (this.amount > sellLimit) {
				this.sell = true;
			}
			// ϶
			this.rent = true;
			return true;
		} else {
			return false;
		}
	}