" We've given them the slip, " he said.

“我们给了他们机会，”他说。

Somehow she’d given them the slip.

【slip】她设法甩掉了他们。

She felt that once Mrs. Vandemeyer gave them the slip, the last hope of finding Tommy would be gone.

她觉得一旦范德迈耶太太给了他们机会， 找到汤米的最后希望就会破灭。