It is arguable that we would be just as efficient with fewer staff.
我们的职员少一些也能发挥同样效率, 这是言之成理的.
I'll say this (for them), (ie I'll admit that) they're efficient.
我得(为他们)说句话, 他们很有能力.
The heating system has recently been modified to make it more efficient.
最近供暖设备已稍加改动以提高效率.