The freight forwarder would prepare all necessary documents for exporter if necessary．

All the risks should be calculated in advance.This is necessary.可改写为：It is necessary that all the risks should be calculated in advance.

Column headings of a table consist of headings that identify the items listed in the columns below them, subheadings as necessary, and units of measurement as necessary.

that all the risks should be calculated in advance. A: This is necessary B: Which is necessary C: That is necessary D: It is necessary

We consider _____ lessons should be previewed before the class. A: that it necessary B: it that necessary C: it necessary that D: necessary it that

____ the unit if necessary. A: Assemble the unit.<br/>use new parts if necessary. B: Reassemble the unit.<br/>use new parts if necessary. C: Rebuild the unit.<br/>use new parts if necessary.

评估所需燃料的数量。 A: Calculate the quantity of fuel necessary. B: Assess the quantity of fuel necessary. C: Do an assessment of the quantity of fuel necessary. D: Do a calculation of the quantity of fuel necessary.

I find ____________ to make some changes. A: it is quite necessary B: that is quite necessary C: it quite necessary D: quite necessary

If_____, we’ll continue our experiment after office hours. A: being necessary B: be necessary C: is necessary D: necessary

If_____,<br/>we’ll continue our experiment after office hours. A: being necessary B: be necessary C: is necessary D: necessary