several

• Det

  Consisting of a number more than one (especially, more than two) but not very many.

• Adj
• Adv
• Noun

experimental

• Adj

  1. Pertaining to or founded on experiment.
  2. Serving to be experimented upon; used in an experiment.
  3. Serving as an experiment; serving to experiment.
  4. Experiential, empirical.

• Noun

models

• Noun

  plural of model

• Verb

were

• Verb

  1. second-person singular simple past indicative of be
  2. first/second/third-person plural simple past indicative of be
  3. first/second/third-person singular/plural simple present/past subjunctive of be
  4. first/third-person singular simple past indicative of be.

• Noun
• Noun

also

1. In addition; besides; as well; further; too.
2. (obsolete) To the same degree or extent; so, as.

developed

• Adj

  1. Industrialized; not third-world.
  2. Mature.
  3. Containing man-made structures such as roads, sewers, electric lines, buildings, and so on.
  4. Having useful or necessary infrastructure.
  5. Advanced, fully formed.
  6. Processed and fixed; containing a visible negative (or positive for slide film) image

• Verb