The phrase "two combinations of" is a correct and usable part of a sentence in written English.
You can use "two combinations of" when you wish to compare or contrast different groupings of two or more items. For example: "The professor presented two combinations of evidence that supported his hypothesis."
Therefore, the combined percentages for these two combinations of variables should not exceed 100%.
As described in the section The strong force, these are the only two combinations of quarks and antiquarks that the strong force apparently allows.
Dr. Watson and Mr. Crick calculated that only two combinations of the four bases -- adenine and thymine, or guanine and cytosine -- could hook together in the space between the sugar-phosphate chains.
The shadow over the organization parted for one evening when the first two combinations of balls ended in favor of the Clippers, who had the third-best chance of winning the first pick in the draft.
The two combinations of adherent materials under study were leather/TR and leather/PU.
Two combinations of Nafion® polymer electrolyte membranes (PEMs) were used in the MEAs.
Two combinations of correlations provided good comparison with data, for thermosyphons with and without NCG.
Two combinations of boundary conditions and three types of loading are considered.
The experimental design was a randomized complete blocks design with three replications and two combinations of lime (with and without).
We utilized two combinations of subjective, objective, and inter-attribute correlation effect significant coefficients to give importance to attributes.
As Achan explained, the trial in Tororo, Uganda, involved 170 children under 5 who were randomized to receive one of the two combinations of antiretroviral drugs.
