• It is necessary to keep the SO 2 level at or below 0.01 mole percent.
• To keep ( or hold ) the temperature down to about 70°F, ...
• It is necessary to keep the SO 2 level at or below 0.01 mole percent.
• To keep ( or hold ) the temperature down to about 70°F, ...
Циммерман М., Веденеева К.. Русско-Английский научно-технический словарь переводчика. Russian-English scientific dictionary for translators. 2012