if need be

在这里need是名词，be是现在虚拟式(见if it be)。if need be的意义为: if there be need = if it's necessary[如果需要(的话)]：

1. I'll work all night if need be. 如果需要的话,我将干个通宵。

2. If need be, help him to do it. 如果需要的话，帮助他干这件事。

3. You are expected to work late if need be. (MED) 如有必要你必须工作到很晚。

4. "How many men were employed to create it?"

“We would use a thousand, ten thousand if need be.” (ODCIE)

“为了把它建起来,你们雇了多少人?”

“如有必要,我们会用1千人,1万人。”