______ both parties have agreed on all the terms and conditions

______ both parties have agreed on all the terms and conditions can we start to prepare the contract.
A、Even if
B、Only when
C、Even though
D、Only while
【正确答案】：B
【题目解析】：only...can sb. do sth.意为“只有....某人才能....."
句意：只有当双方都同意所有条款后，我们才能开始准备合同。