語態指的是句子中的主語和謂語之間的關係。當句子的主語是謂語的執行者時，其謂語形式為主動語態(Active Voice)，當主語為謂語的承受者時，其謂語的形式為被動語態(Passive Voice)。
在被動語態的句子中，其主語往往是主動語態句子中謂語動詞的賓語。因此，被動語態句子中的謂語動詞必須是及物動詞。
試比較：
We also determined four crystal structures of SPE 7 complexed with four different antigens.(主動語態)
Four crystal structures of SPE 7 complexed with four different antigens we alsodetermined.(被動詞態)
語態決定於句子強調的是執行者還是承受者。當句子強調的是謂語動作的行者時，則採用主動語態。
To overcome these problems we have studied the biotransformation of foreign substrate by plant-cultured suspension cells.
當句子強調的是謂語動作的承受者時，則採用被動語態。
β-Lactams canbe transformed into valuable β-amino acid which are of immense interest from both pharmacological and chemical viewpoints.
在英語科技論文的表述中，被動語態的句子用得較多，但被動語態用詞較多，使句子長或頭重尾輕，故通常能用主動語態表述的內容可儘量不用被動語態表述。
A facile transformation of 3,4- -disubstituted 2-azetidinones to chiral 5,6- dihydro-2-pyridones, which can serve as valuablechiral intermediates for different piperidine and indolizidine alkaloids andazasugars, was reported by Lee et al.
此句明顯頭大尾小，給人一種句子不穩的感覺，若改成如下的主動句，則可克服這一毛病。
Lee et alreported a facile transformation of 3, 4-disubstituted 2-azetidinones to chiral 5, 6-dihydro-2-pyridones, which can serve as valuable chiral intermediates fordifferent piperidine and indolizidine alkaloids and azasugars.
在被動語態的句子中，凡是有動詞時，則不用該動詞相應的名詞，以使句子簡練。
Separation of the compounds was accomplished 可改成Thecompounds were separated.
科技英文論文的表述中，常見的這類名詞及其相應的動詞如下：
determinationdetermine,identificationidentify,speculationspeculate , discussion discuss, descriptiondescribe , treatmenttreat , assignmentassign ,interpretationinterpret , explanationexplain , calculationcalculate,differentiationdifferentiate, synthesissynthesiz, preparationprepare,dissolutiondissolve,dilutiondilute,concentrationconcetract,evaporationevaporate,extractionextract,analysisanalyze
由形式主語 it 代替主語從句先行所引出的被動句是常見的一種表述形式。
It has recently been reported by Mateo et al. that some immobilization methods can enhance the thermostability of an enzyme.
但在不影響句子表述內容的情況下可改成主動句：
Meteo et al. has recently reported that…