We know that the problems related to mining activities are very complex.
In fact, people are very complex, strange and selfish beings.
The civil aviation regulations are very complex.
The matters we have to deal with are very complex.
The reasons for such high rates of illiteracy are very complex.
The movements are very complex and promote the interaction of all muscles.
Les mouvements sont très complexes et favorisent l'interaction de tous les muscles.
The answer to these questions and problems are very complex.
Les réponses à ces questions et les problèmes sont très complexes.
Their wines are very complex, intense, structured and meaty.
Leurs vins sont très complexes, intenses, structurés et charnus.
The flavours and aromas of this strain are very complex.
Les saveurs et les arômes de cette variété sont très complexes.
The effects within the user are very complex and difficult to predict.
Les effets sur le consommateur sont très complexes et difficiles à prévoir.
The social issues posed by these shantytowns are very complex.
Les problèmes sociaux posés par ces bidonvilles sont très complexes.
Some movements like running are very complex, but almost automated.
Certains mouvements comme la course sont très complexes, mais presque automatisés.
Some of these cases, as you said, are very complex.
Comme vous l'avez dit, certains de ces cas sont très complexes.