语法结构 than + be + 形容词
与 than + be + 过去分词 （被动语态）一样，than + be + 形容词 （系表结构）也是固定的表达句式。通常以下列三种方式表达：
A. than 前面是形容词或副词比较级
He wouldn’t keep her here any longer than was absolutely necessary, would he?
除非必要，他不会把她留在这里太久，对吧?
But the true costs of holding the tournament are more manageable than is commonly feared.
但举办联赛的真正成本比人们通常担心的要容易控制得多。
I have received more compliments and more flattery than is healthy for me.
我收到了太多的赞美和奉承，对我没什么好处。
Paul visited the local bars more frequently than was decent for a senior lecturer.
作为一个高级讲师，保罗去当地酒吧的次数太频繁了。
Her pity for the man she had hurt so deeply made her behave more kindly towards him than was perhaps sensible.
她对这个被她深深伤害过的男人的同情，使她对他的态度变得更加亲切，这也许是不理智的。
Somehow he had landed on his backside and then had felt his tailbone knock the earth harder than was safe.
不知怎么的，他是仰面着地的，然后感到尾骨重重地撞在地面上，超出了安全范围。
The local variety of sour cream, smetana is often sweeter than is common in the West, closer actually to heavy cream.
当地的酸奶油，斯美塔那通常比西方常见的更甜，实际上更接近浓奶油。
The interference must go no further than is strictly necessary to achieve its permitted purpose.
干涉不得超出达到允许目的的严格必要范围。
B. than 前面是 more/less + 名词
A number of new technologies will enable much more rapid development than was previously possible.
许多新技术将使发展速度比以前快得多。
Teachers, parents, and students all need access to better information about colleges and careers than is commonly available.
老师、家长和学生都需要获得比通常更好的关于大学和职业的信息。
The detail of this book requires more explanation than is possible here, but this is a rewarding book to read.
这本书的细节需要更多的解释，但这是一本值得一读的书。
Thanks to virtual memory technology, software can use more memory than is physically present.
由于虚拟内存技术,由于虚拟内存技术,软件可以使用比实际存在的更多的内存。软件可以使用比物理上更多的内存。
When iron is smelted from its ore, it contains more carbon than is desirable.
铁刚从矿石中熔炼出来时，它所含的碳比所需要的要多。
Both countries continue to spend far more on arms than is prudent or necessary.
这两个国家在武器上的花费仍然远远超过了谨慎和必要的程度。
Captain Dawson sensed that there was more behind the request than was readily apparent.
道森上尉觉察到，这个请求的背后隐藏着更多的东西。
Employees subscribed for far more shares than were available.
员工认购的股票远远超过了可获得的数量。
The company pioneered the use of larger, more economic goods wagons than were usual in Britain.
该公司率先使用比英国通常使用的更大、更经济的货车。
C. more than + be + 形容词
I do not wish to complicate the task more than is necessary.
我不希望把这项任务弄得过于复杂。
He had disbursed more than was customary with him on the hotel where they had spent the night.
他在他们过夜的旅馆上花的钱比平时多。
Perhaps he was urging people to do more than is morally required of them.
也许他是在敦促人们做超出道德要求的事情。
Perhaps even more than is usual in the social sciences, theory is closely related to practice.
理论与实践的密切联系可能比社会科学中通常的情况更加密切。
Sharing data requires clinicians to trust one another, and non-clinical colleagues, far more than is common at the moment.
共享数据需要临床医生彼此信任，以及非临床同事之间的信任，这远远超出了目前的普遍水平。
They are afraid of incriminating themselves and say no more than is necessary.
他们害怕牵连自己，只说必要的话。
Also you pull in more than is desirable or necessary for the optimum climb rate when you’re on the control bar.
此外，当你在控制杆上时，你的拉入超过了理想或必要的最佳爬升速度。