The phrase "a primary line" is correct and usable in written English.
It can be used to refer to a main or essential line of thought, argument, or text in various contexts, such as writing, design, or communication.
Example: "In the report, the author emphasized a primary line that highlighted the importance of sustainability in business practices."
Alternatives: "a main line" or "a key line".
However Portugal's Polícia Judiciária (PJ) claimed that Wednesday's press conference simply confirmed a primary line of investigation which has been investigated by Portuguese police since last October.
Macrophages represent a primary line of defence against foreign materials.
During the Qin-Han period, the reconstruction of this wall was used by the agricultural peoples as a primary line of defense against nomadic invaders.
I don't advocate brandishing knives as a primary line of self-defence.
I don't advocate brandishing knives as a primary line of self-defense.
The acidity of the stomach is a primary line of host defense against food borne pathogens.
Clearly, however, even if such novelties turn out to be numerically prominent, they are, typically, involved in ancillary functions and hardly can be construed as the heritage of a distinct primary line of cell evolution [ 74].
Telomerase inhibition reduced proliferation in two established cell lines and a primary TIC line (Fig. 2a c) through shortening of telomeres (Fig. 2g i) and induction of senescence (Fig. 3d f).
Macrophages constitute an important and primary line of defense against any infection.
Imetelstat, a phase 2 telomerase inhibitor, was used to elucidate the effect of telomerase inhibition on proliferation and tumorigenicity in established cell lines BXD-1425EPNN, R254), a primary TIC line (E520) and xenograft models of pediatric ependymoma.
This suggests Cyanobacteria as a primary bacterial line of descent predate oxygenic photosynthesis.
