My teacher always tells me that whenever I am using the preposition "by", I should use the perfect tense, whilst the simple tense is appropriated when I am using "in". For example:
- By 2010, exports had shrunk to £500mln
- Exports will reach £2bn in 2035
I am doing a writing and I am not sure if this sentence is correct:
By 1970 it [the services inductry sector] already employed more people than the other three industries combined, and in 2010 it reached its highest figure
I am using by and then a simple tense. However the following sentence doesn't sound right to me:
By 1970 it [the services inductry sector] had already employed more people than the other three industries combined
mainly because this is not true, since in previous years other industries employed a myriad of people. What I am trying to say is that in 1970, manufacturing employed more people than the other three sectors combined in 1970, not that it had employed more people taking into account the employees of the past because that is not true.