The phrase "as he underlines" is correct and usable in written English.
It can be used when referring to someone emphasizing a point or highlighting something important in their speech or writing.
Example: "In his lecture, he made several key points, as he underlines the importance of critical thinking in education."
Alternatives: "as he emphasizes" or "as he highlights".
He echoed Shapiro, or Shapiro echoed him, as he underlined the delicate balance that lay before his young country: negotiating rapid modernization combined with an ardent desire to remain committed to one's culture and heritage.
He came up with several models for social responsibility as he underlined that CSR involved a degree of voluntarism, as opposed to coercion.
The unbeaten Dawn Approach made it look easy as he underlined his 2013 Classic credentials with victory in the Dewhurst Stakes at Newmarket.
In the men's competition, Delhi silver medallist Kirkbride came within a whisker of a new Scottish record of 191kg for the clean and jerk as he underlined his medal potential for the event to be held in Glasgow's Clyde Auditorium.
But the busy staging, by Deborah Warner, undercut as well as underlined the play's insights and moments of revelation.
As well as underlining the golden rule of learning – you have to practice – Ericsson's idea also has a strong egalitarian air.
Johnson spoke to two members of Trump's transition team – former House speaker Newt Gingrich and senator Jeff Sessions – on Friday, as he sought to underline Britain's determination to strike up a close working relationship with the new regime in Washington.
After praising Mr. Kerry's military service, his 20 years in the Senate -- "though I'm not so sure I admire his record" -- Mr. Bush highlighted what he called Mr. Kerry's changing position on Iraq, as he sought to underline what has been a continuing effort by his campaign to portray Mr. Kerry as inconsistent.
