A semiconductor is a substance that has an electrical conductivity between a metal and an insulator. According to this definition, which of the following is wrong with the following statement? ['A solution is not as conductive as a metal and is not an insulator. Therefore, this solution is a semiconductor.', 'Dry wooden blocks are non-conductive, and they become conductive when they get wet, but the conductivity is far less than that of aluminum, copper and other metal materials. Some people say that "wet changes wooden blocks from insulators to semiconductors" are wrong.', 'The conductivity of mercury is much less than that of aluminum, copper, iron and other metal materials, so mercury is a semiconductor substance.', 'After doping certain element atoms in pure crystalline silicon, it will change from non-conductive to conductive. However, it is easier to conduct electricity in one direction than the other, and its conductivity is greatly affected by external factors such as voltage. These conductive properties are not as good as metals, so silicon is a semiconductor substance.']