Nhận biết (M1)

An emulsifier is a type of compound that serves to stabilize an emulsion — a mixture of two or more liquids that otherwise would not easily blend together, like oil and water. Though modern chemists commonly use emulsifiers like poloxamer 407 in their formulations, emulsifiers that have been employed for millennia, such as beeswax and egg yolk, __________ used to this day by chemists as well.

Which choice completes the text so that it conforms to the conventions of Standard English?

• A.

  are

• B.

  would have been

• C.

  were being

• D.

  were