We'll go slowly to begin with.

我们开始时会慢慢来的。

He spoke well to begin with, but then started rambling and repeating himself.

开始他说得很好，但是后来开始闲扯，一句话翻来覆去地讲。

"What do scientists you've spoken with think about that?"—"Well, to begin with, they doubt it's going to work."

“和你交谈过的科学家们对此怎么看？”——“噢，首先，他们怀疑这是否会奏效。”

"To begin with," said the Cat, "a dog's not mad."

“首先，”猫说，“狗是不疯的。”

To begin with, you must work hard at your lessons and be fully prepared before the exam. Without sufficient preparation, you can hardly expect to answer all the questions correctly.

首先，你必须努力学习功课，并在考试前做好充分的准备。没有充分的准备，很难正确回答所有的问题。