Can I say : Let's welcome sb to do sth? For example: Let's welcome Jack to give us an introduction about urbanisation.

Which sentence is correct? The two sentences differentiate in the usage of who/m. 1. The boy of whom everyone who knew him said he was naughty has now become a successful businessman. 2. The boy who everyone who knew him said he was naughty has now become a successful businessman.

Is this structure correct? Possible as it seemed that this man would make a fortune, he finally lost all his money.

Based on grammar only, is this sentence correct? According to the report, nearly 4600 people survive death due to infection of respiratory tract, as many as the number lost to the covid-19.

Is this sentence correct? This is where the problem is.

Is that sentence correct? China has more English learners than the US has English speakers.

Is this sentenece grammatically correct? Advertisement disseminate the information of goods to attract consuners to buy them, for which phenomenon many people argue that nowadays people are buying things not for their real needs. I find two sentences on the Internet that shows the usage of 'for which phenomenon'. 1. During the fall the sun is obscured and objects assume yellow or ashy hue, as during an eclipse of the sun, for which phenomenon the mist were usually mistaken by the ancient chroniclers. 2. There are nearly always gender aspects to genocides, for which phenomenon the term “gendercide” was first proposed by Mary Ann Warren (1946-2010) and then appropriated by Jones and others.

Is this sentence correct? I find it a little weird. Even before the coronavirus hit, trouble was brewing in the land of unicorns, as tech startups worth more than $1bn are called.